IRSPAS 2016
Permanent URI for this collectionhttp://repository.kln.ac.lk/handle/123456789/15651
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Item The 3D atomic scale and electronic structure characterization of novel fcc ruthenium nanoparticles using synchrotron light source(Faculty of Science, University of Kelaniya, Sri Lanka, 2016) Kumara, L.S.R.; Sakata, O.; Kohara, S.; Song, C.; Yang, A.; Kusada, K.; Kobayashi, H.; Kitagawa, H.Ruthenium (Ru) is a 4d transition metal that in the bulk adopts hexagonal closepacked (hcp) structure at all temperature ranges, and novel face-centered cubic (fcc) Ru nanoparticles (NPs) have been observed to be more efficient than conventional hcp Ru NPs larger than 3 nm. It has recently attracted much attention as a potential application in removal of car exhausts due to high catalytic activity for CO oxidation and preventing CO poisoning in fuel-cell system. We here report the 3-dimentational atomic-scale structures of fcc and hcp Ru NPs using high-energy X-ray diffraction (HEXRD), Rietveld analysis, pair distribution function (PDF), and reverse Monte Carlo (RMC) modelling. Hard X-ray photoelectron spectroscopy (HAXPES) can provide important information on the influence of NP size on electronic properties. The HEXRD and HAXPES of Ru NPs were performed at BL04B2 and BL15XU at SPring-8, the world largest third-generation (8 GeV) synchrotron radiation facility located in Hyōgo prefecture, Japan. We observed higher stability of the lattice distortion of fcc Ru NPs with increasing particle size. The PDF analysis results show that the structural disordered Ru NPs at short- to intermediate-range atomic distances. The order parameter for fcc Ru NPs decreased with increasing particle size due to the loosely packing atomic arrangement and may explain an origin of higher catalytic activity of fcc Ru NPs. In this study, the observed trend of increasing catalytic activity of fcc Ru NPs was also discussed using their core-levels and valence band electronic structures. This work was partly supported by ACCEL, Japan Science and Technology Agency (JST) and also partly supported by Ministry of Education, Culture, Sports, Science and Technology of Japan (OS: 15K04616).Item Accelerating the rate of convergence of some efficient schemes for two-stage Gauss method(Faculty of Science, University of Kelaniya, Sri Lanka, 2016) Chamaleen, D.B.D.; Vigneswaran, R.The non-linear equations obtaining from the implicit s – stage Runge-Kutta methods have been solved by various iteration schemes. A scheme has been developed, which is computationally more efficient and avoids expensive vector transformations. The rate of convergence of this scheme is examined when it is applied to the scalar test differential equation = and the convergence rate depends on the spectral radius [()] of the iteration matrix (), where = ℎ and ℎ is the step-size. In this scheme, supremum of a lower bound for [()] is minimized over the left half - plane with the constraints requiring super-linear convergence at = 0 and → ∞ .Two new schemes with parameters are obtained for the two-stage Gauss-method. Numerical experiments are carried out in order to evaluate and compare the efficiency of the new schemes and the original scheme. Consider an initial value problem for stiff system of ordinary differential equations = (), () = , : ℝ → ℝ. An s-stage implicit Runge-Kutta method computes an approximation to the solution x () at discrete point = + ℎ by = + ℎ Σ ( ), where , ,…,, satisfy sn equations + ℎ , ), = 1,2, . . . , . = is the real coefficient matrix and = [ , ,…,] is the column vector of the Runge-Kutta method. Let = ⊕ ⊕ … ⊕ ∈ ℝand () = () ⊕ () ⊕ … ⊕ () ∈ ℝ. Then the above equation in , ,…, may be written by = ⊗ + ℎ( ⊗ )(), where = (1,1, … ,1) and ( ⊗ ) is the tensor product of the matrix with × identity matrix . The efficient scheme, which has been already proposed, is given by [ ⊗ ( − ℎ)] = ( ⊗ )( ⊗ – ) + ( ⊗ )( ⊗ – ) + ℎ( ⊗ )() + ℎ( ⊗ )(), = 1,2, …, In this scheme, supremum of a lower bound for [()] is minimized over ℂ, where ℂ = { ∈ / () ≤ 0 } with the constraints [()] = 0 at = 0 and [()] = 0 at → ∞. The parameters for the two-stage Gauss method are obtained and Numerical experiments are carried out.Item An AHP approach to prioritize the distributor’s requirements while minimizing the transportation cost(Faculty of Science, University of Kelaniya, Sri Lanka, 2016) Madushika, I.K.; Wijayanayake, A.Academic and corporate interest in Supply Chain Management (SCM) has risen considerably in recent years as SCM has emerged as one of the major areas for companies to gain a competitive advantage. Basically, the three fundamental stages of a Supply Chain (SC) are, procurement, production and distribution. Among these three stages, distribution plays a vital role as it directly impacts both the SC cost and customer experience. Many models have been developed in the past to minimize transportation cost under different constraints, as the main cost of logistics is transportation. In fact, when the organizations run on cost cutting approaches, not all the customers are satisfied when the demand surpasses the supply. Therefore, to retain the most important customers a proper mechanism is needed to prioritize them. Previous studies have been addressed different problems in logistics and improved models have been developed to maximize the service level and customer satisfaction but prioritization of customers is still a gray area which remains in the logistics literature. One of the main hurdles for distributors is handling situations, where the demand is higher than the supply and selected set of orders have to be delivered. Therefore, the main objective of the study is to identify the most important customers to be delivered first, from the distributor’s perspective while minimizing the cost of transportation. In this study, Analytic Hierarchy Process is used to identify the most important customers to the organization, under different criteria, defined by the distributor. All the criteria and alternatives were compared pair-wisely to calculate the overall importance of the alternatives. A mixed integer linear programing model has been developed with priority values in order to minimize the transportation cost. The proposed model will satisfy the needs of the important customers first and then the rest of the customers will be satisfied with the remaining quantities. When comparing the results of the developed model and ordinary transportation model, the transportation cost is higher in the developed model than the general transportation model. However, the satisfactory level of meeting the demands of the important customers is almost 100%. Therefore, this model is more appropriate for the firms who value customer needs more than minimizing the transportation cost.Item An algorithm for plagiarism detection in Sinhala language(Faculty of Science, University of Kelaniya, Sri Lanka, 2016) Basnayake, S.F.; Wijekoon, H.; Wijayasiriwardhane, T.K.According to the Merriam-Webster dictionary, the simple definition of the verb plagiarize is, “to use the words or ideas of another person as if they were your own words or ideas”. Many software tools to aid in detecting plagiarism is available for English language, but equivalent tools are not yet available specifically for Sinhala language. Though language independent tools that work on many languages are available, they generally give poor results as they do not consider language specific features. There are some detection methods proposed for Asian languages like Hindi, Malayalam, Arabic and Persian which have some close relationship and similar properties of Sinhala language. All of those methods use language specific rules and they even outperform the commercially available tools. These findings are evidence that the language specific plagiarism detection is more effective than the language independent plagiarism detection as some paraphrasing techniques can be used to mislead the language independent systems.Sinhala language is constitutionally recognized as the official language of Sri Lanka, along with Tamil. Due to the complexity of the language structure and rules of grammar, the language independent tools seem to provide poor results when used for plagiarism detection in Sinhala documents. In this research, we propose a novel plagiarism detection algorithm built around content based methods specific to Sinhala language. The methodology of this study follows both experimental and build approaches. The proposed plagiarism detection system has two modules namely, text pre-processing module and the similarity detection module. The text pre-processing module pre-process the text files to standardize the text sources using techniques such as stop word removal, number replacement, lemmatization, synonym recognition and creating n-grams. Then the similarity detection module analyses the pre-processed text using Jaccard coefficient and cosine similarity coefficient to measure the similarity between two documents. A prototype of Sinhala language plagiarism detection system will be implemented using the proposed method and several combinations of the above techniques will be used to discover the best combination. Testing and statistical performance evaluation will be carried out using a sample of source text files and plagiarized text files in Sinhala language by taking expert judgements also into the consideration. The final outcome of this research study is to develop an effective software application for plagiarism detection in Sinhala language documents.Item Analysing mobility patterns of people to determine the best transportation method(Faculty of Science, University of Kelaniya, Sri Lanka, 2016) Senanayake, J.M.D.; Wijayanayake, W.M.J.I.With the technological enhancements related to Internet, Wireless Communication, Big Data Analytics, Sensor-based Data, and Machine Learning; new paradigms are enabled for processing large amount of data which are collected from various sources. In the past decades, both coarse and fine-grained sensor data had been used to perform location-driven activity inference. In recent years, GPS phone and GPS enabled PDA become prevalent in people’s daily lives. With such devices people become more capable than ever of tracing their outdoor mobility and using locationbased applications. Based on the collected data from these GPS enabled devices with the help of IoT related to user mobility lots of research areas are opened. In this research the data related to user locations when users do any outdoor movements is collected using the mobile devices that are connected to the Internet and is mined using data mining techniques and come up with an algorithm to model & analyse those big data to identify mobility pattern, traffic prediction, transportation method satisfaction etc. The data for this research will be collected using a mobile application which has to be installed in smart devices like smart phones, tablet PCs etc. In this application the user has to enter the activity that he or she currently doing and the method of transportation & the users' opinion on the transportation method if he is doing some sort of travelling. The GPS coordinates (longitude & latitude) as GPS trajectories along with the time stamp and the date will be automatically acquired from the users' IoT device. A cloud based storage will be used to store collected data. Since the dataset is going to be a huge one, there can be data which contains outlier values due to the uncertainty of the mobile network coverage and the GPS coverage of the devices. Therefore, these data should be properly cleaned when doing data mining activities otherwise these data will lead to incorrect results such as wrong traffic prediction in certain places if several users are stuck in the same GPS coordinates for a while. Not only that but also when it comes to the user satisfaction, it might lead to generate incorrect outcome if the users in the sample will not enter their satisfaction accurately. This can be avoided by comparing cluster wise users with the consideration of the location and the transportation method. We can get the average opinion of the users and take it as the satisfaction of the transportation method in that cluster. Using the final results of this research the government can also be benefited if we selected the sample users well with mixing all the types of people and by providing necessary information for planning smart cities.Item Analysis of a stochastic predator-prey model(Faculty of Science, University of Kelaniya, Sri Lanka, 2016) Prasadini, K.D.S.; Mallawa Arachchi, D.K.In biological systems Lotka-Volterra predator-prey model describes the population dynamics of two interacting species of predators and its preys. Classical predatorprey model is a primitive deterministic model governed by the two differential equations, namely, = ( − ) and = ( − ) where and denote prey and predator respectively, and , , and are parameters. This model can be improved by introducing stochasticity that accounts for the random fluctuations of a realistic predator-prey dynamical system. In this research work, we use Stochastic Differential Equation (SDE) approach. There are various ways, based on various assumptions, to incorporate SDE. One common approach is to use equations of the following form: = ( − ) + ( + ) = ( − ) + ( + ) These types of Stochastic Differential Equations (SDE) can be simulated in Matlab using numerical methods such as Euler-Maruyama method. Phase planes of the deterministic and stochastic models are carried out to demonstrate the behavior of this modified model. Our initial goal is to compare different stochastic models with the original deterministic model through simulations. The deterministic model has a positive equilibrium which is globally stable for positive values of the parameters. Nevertheless, in the stochastic model, the predator and prey populations may tend to extinction. Extinction percentages of predator or prey population are summarized and analyzed through this research work.Item Analysis of a stochastic predator-prey model(Faculty of Science, University of Kelaniya, Sri Lanka, 2016) Prasadini, K.D.S.; Mallawa Arachchi, D.K.In biological systems Lotka-Volterra predator-prey model describes the population dynamics of two interacting species of predators and its preys. Classical predatorprey model is a primitive deterministic model governed by the two differential equations, namely, ���� = (������ − ��������) ���� and ���� = (�������� − ������) ���� where �� and �� denote prey and predator respectively, and ����, ����, ���� and ���� are parameters. This model can be improved by introducing stochasticity that accounts for the random fluctuations of a realistic predator-prey dynamical system. In this research work, we use Stochastic Differential Equation (SDE) approach. There are various ways, based on various assumptions, to incorporate SDE. One common approach is to use equations of the following form: ���� = (������ − ��������) ���� + ��(���� + ����)�� ������ ���� = (�������� − ������) ���� + ��(���� + ����)�� ������ These types of Stochastic Differential Equations (SDE) can be simulated in Matlab using numerical methods such as Euler-Maruyama method. Phase planes of the deterministic and stochastic models are carried out to demonstrate the behavior of this modified model. Our initial goal is to compare different stochastic models with the original deterministic model through simulations. The deterministic model has a positive equilibrium which is globally stable for positive values of the parameters. Nevertheless, in the stochastic model, the predator and prey populations may tend to extinction. Extinction percentages of predator or prey population are summarized and analyzed through this research work.Item An analysis of software development process models and their applications in software industry(Faculty of Science, University of Kelaniya, Sri Lanka, 2016) Wijesekara, G.L.A.; Wickramaarachchi, D.N.The development of software takes into account a lot of different tasks until the software is released. The order in which these tasks are done is called the software development life cycle. When software development projects become larger and much complicated, it becomes more difficult to manage the software development process and issues such as updating software features and fixing errors came to attention. Thus methodologies named software process models which consist of set of specific activities have been developed. These software process models were introduced to address issues with changing clients’ requirements, product quality, cost, time etc. When the software process model is not properly suitable for developing software, ultimately the end software product will be affected. On the other hand, each of these model’s effectiveness varies with project circumstances. It is widely acknowledged that no single model is effective in all situations. At present, the most of software development companies have their own process models and standards in developing software due to increasing complexity of software projects and high demand for the software project success. They have been adding customization to theoretical process models according to projects’ characteristics and improving software development process to deliver better software products. However, there is lack of studies about real world, currently implementing software process models in software industry and about the changes/improvements in those process models according to projects characteristics thus creating a knowledge gap about what are the new changes/improvements in process models in current industry. In this research, we focus on this gap and a survey is conducted on 25 software projects from various software development companies. Through the survey it is found out about currently implementing software process models in different types of software projects and what are the new customizations done to those software process models according to the project characteristics. Finally we come up with suggestions to tailor software process models according to software projects and discover new trends in software process models.Item Analysis of the error in an iterative algorithm for solution of the regulator equations for nonlinear parabolic control system(Faculty of Science, University of Kelaniya, Sri Lanka, 2016) Hansameenu, W.P.T.; Aulisa, E.; Gilliam, D.This work is based on the classical geometric method, which in turn is based on the classical geometric regulation theory, which involves asymptotic tracking and disturbance rejection for nonlinear parabolic control systems. The classical geometric method is based on the solution of a coupled pair of operator equations referred to as regulator equations. In general, solving the regulator equations or even obtaining accurate numerical solutions for the simple control problem is not an easy task. In fact, most of the time the classical geometric method gives the solvability conditions of the regulator problem, rather than the actual solution. We present a methodology for tracking and disturbance rejection, which is more general than the one based on the regulator equations, and can be applied to general smooth signals. This methodology is based on an iterative method known as the - iterative method for obtaining approximate solution for the regulator problems for a class of infinite dimensional linear control systems. This work describes the error analysis for this iterative method regarding more general references and disturbances. In this work we consider bounded input and output operators. In particular, we obtain estimates showing geometric convergence of the error, controlled by the parameter . In addition, we demonstrate our estimates on a variety of control problems in multi-physics applications by numerically solving the -iterative algorithm by using the finite element solver “COMSOL”.Item Antioxidant activities in extracts of five plant sources on stabilization of stripped sunflower oil and egg yolk homogenate(Faculty of Science, University of Kelaniya, Sri Lanka, 2016) Senanayake, C.M.; Seneviratne, K.N.out to evaluate the antioxidant potential of five natural sources namely, coconut cake (A), Psidium guajava L. leaf (Guava) (B), Psidium guineense Sw. leaf (Ambul guava) (C), rice bran (D) and sesame cake (E) in both chemical and food model systems (stripped sunflower oil and egg yolk homogenate). Phenolic substances from the test plant materials were extracted using ethanol:water (70:30) solvent system. Total phenolic content (TPC) was determined using Folin-Ciocalteu method and expressed as gallic acid equivalents (GAE) per kilogram of sample. Antioxidant activities of extracts and butylated hydroxytoluene (BHT) were evaluated using deoxyribose degradation assay after adjusting the concentration to 30 μg mL-1. Antioxidant activities of phenolic extracts on stripped (antioxidant free) sunflower oil were determined by comparing the induction time (IT) using the Rancimat Apparatus at 100 0C. Effect of phenolic antioxidants on the inhibition of thiobarbituric acid reactive substances (TBARS) formation was evaluated using egg yolk homogenate as the food model system. Results of TPC as GAE vary in the order, C (195.25±9.56 g/kg) > B (68.83±3.74 g/kg) > D (4.14±0.46 g/kg) > E (2.11±0.29 g/kg) > A (0.77±0.03 g/kg). Phenolic extract of C showed a significantly (p<0.05) higher percentage inhibition of deoxyribose degradation (76.5±1.5 %) than other phenolic extracts and BHT. Inhibition percentages obtained for A, B, D, E and BHT were 39.5±1.4 %, 71.0±2.7 %, 46.1±3.1 %, 42.1±2.5 % and 32.6±2.1 % respectively. Results of IT of stripped sunflower oil and inhibition % of TBARS formation were stated in Table 1.Item Applicability of unsupervised learning algorithms for setting profiles for consumer buying behavior(Faculty of Science, University of Kelaniya, Sri Lanka, 2016) Paranavithana, I.R.; Rupasinghe, T.D.The Consumer Buying Behaviour consists of a summation of attitudes, preferences, intentions and, decisions taken by them. The process that customer buys a product or service varies for each individual and each category of products they may purchase. With the development of Information Technology, the products and the behaviour of purchasing those products have drastically changed and become more unique to individuals. With respect to these changes, the data collection and analysis have become more dynamic and customer data has become larger and nosier in terms of volume and complexity. As a result of that, handling, analysing, and interpreting customer Point of Sale (POS) data has become a challenge for Retail Supply Chains (RSC) who wish to segregate customers into specific niche markets. Furthermore, it makes increasingly difficult for the retailer to find out when a person comes and buys the products from their outlets and to predict his/her behaviour for the subsequent purchases. As a solution for the aforementioned problems faced by the retailers, a novel a consumer buying behaviour profile mechanism is proposed. The profiles are created with respect to the frequency, time-stamp, and product category using a large POS dataset. The Unsupervised learning techniques were utilized in categorizing consumers in determining similar purchasing behaviour using K-means, Expectation Maximization, and Hierarchical Agglomerative Clustering (HAC). Along with the above clustering techniques, text mining techniques were used in categorizing the product descriptions to create the desired product categories. The study has used data from the UCI machine learning repository with 541,909 POS type records and has applied the aforementioned unsupervised learning techniques to setup the profiles. It has unveiled product related and non-product related charateristics for the given POS data and has laid a novel foundation to construct the profiles to determine buying behaviour. Furthermore, these profiles can be used in segmentation of consumers, RSC specific promotions, and to predict future possibilities to minimize inventory related problems.Item An approach to personalize learning using big data analytics for higher education(Faculty of Science, University of Kelaniya, Sri Lanka, 2016) Jabir, A.; Rajapakse, C.The concept of BYOD (Bring Your Own Device) has gained popularity in studentcentered learning and higher education institutions make significant investments on improving the wireless network to enhance this. Virtual Learning Environment and Learning Management Systems were introduced and personalization of learning becomes the next milestone. The huge streams of data produced by these Wi-Fi networks makes ground for Big Data analytics to identify opportunities in educational environments to adopt personalized learning. The term ‘Personalization’ refers to the tailoring of content and recommending items by inferring what interests a user based on previous or current interactions with that user, and possibly other users. This research proposes an approach to personalize learning on an online learning platform by providing personalized recommendations of educational web resources, comparative feedback and allocate personalized bandwidths based on the concept of deprioritization (lowering priority ranks of heavy users). Concepts of Big Data analytics and data mining techniques will be used to satisfy the objectives. The approach consists of offline phase (modelling phase) and online phase (recommendation /deprioritization) phase. In the offline phase, models will be developed for recommendation and deprioritization separately. For recommendation a hybrid filtering method will be used. k-Nearest Neighbour, a user-based collaborative filtering technique, will be used with correlation based similarity measure with demographic filtering based on demographic classifiers (faculty, year, General/Special/Honors, GPA) to eliminate the cold start problem. To increase the efficiency and accuracy, k-means clustering will be used as an intermediate step to determine usage clusters to group users exhibiting similar browsing patterns and page clusters to discover pages with similar access patterns. For this the access logs of the University of Kelaniya’s Wi-Fi network will be utilized. The parameters for usage clustering would be the timestamp, web resource and category (education, social networking, gaming etc.) whereas the parameters for page clustering would be category and temporal concepts. In the online phase, first the cluster that the current active user belongs to will be identified and k-NN will be applied on that particular cluster to recommend web resources. These techniques also provide the basis for comparative feedback compared to top scorers of the same area of major. For personalized allocation of bandwidth a separate k-means clustering will be performed to identify heavy users during the offline phase. During the online phase deprioritization will be applied accordingly if the current user belongs to the heavy users cluster and there is a heavy traffic in the network. Cross validation will be used to evaluate the models.Item Arboreal ant assemblages (Formicidae) and importance of Oecophylla smaragdina (Fabricius) occurrence in a wet zone cashew field in Sri Lanka(Faculty of Science, University of Kelaniya, Sri Lanka, 2016) Dias, R.K.S.; Perera, A.P.S.Many ant species (Hymenoptera, Formicidae) have the potential to control herbivore abundance, reducing the plant damage while increasing plant growth, reproduction and yield in agro-ecosystems. Ant assemblages on six cashew trees in Delgoda, Gampaha District were recorded throughout three phenological phases by visiting the field six times from March to June in 2015. Seven to 15 baited traps were set 25 cm apart on the branches of each small, medium and large tree and collected after three hours. Worker ants seen on the main trunk and four major branches of each tree during a five minute period were hand-collected 5 to 9 times from small to large trees on each occasion. Collected ants were preserved in 70% ethanol, identified and listed. Number of Oecophylla smaragdina (Fabricius) nests observed on the same trees was recorded from April to June in 2015. The materials carried by O. smaragdina workers on cashew tree branches were also collected, preserved in 70% ethanol and identified to the possible levels using a Low Power Stereo-microscope. Fourteen ant species in five subfamilies were recorded. Species richness observed on each occasion ranged from 7 – 11 while O. smaragdina was the only species on all cashew trees. Nests of the species of O. smaragdina were observed only on one or two large and medium-sized trees. Various plant and animal materials carried by O. smaragdina workers confirmed that the species is an omnivore and a generalist predator. Presence of ant assemblages on cashew trees in the absence of any insecticide application in the current cashew field may have contributed to an observed absence of serious damage by cashew insect pests elsewhere.Item Assessing potential biological hazards associated with Kelani River water using Nile tilapia (Oreochromis niloticus) as an aquatic model species(Faculty of Science, University of Kelaniya, Sri Lanka, 2016) Ruvinda, K.M.S.; Pathiratne, A.Kelani River receives complex mixtures of pollutants from diverse sources which include waste from industries, agriculture, domestic and municipal sources. However, scientifically based evidences on biological impacts associated with the Kelani River water are limited. Nile tilapia (Oreochromis niloticus) is a practically feasible aquatic model for toxicological assessments under tropical conditions. The present study assessed erythrocytic nuclear abnormalities (ENA), hepatic ethoxyresorufin O-deethylase (EROD) and hepatic glutathione S-transferase (GSTs) activities of Nile tilapia following exposure to selected surface water samples collected from the Kelani River and its tributaries in order to assess the potential biological impacts. Fingerlings of fish were exposed to surface water samples from an industrial effluent receiving canal (Menikagara ela; Site B), canal confluent (Site M), downstream of Kelani river at Sedawatta (contaminated with oil installation complex effluents and house hold waste; Site S) and up stream of Kelani river at Ruwanwella (reference site; Site R) and aged tap water (as controls) for 10 days under static renewal conditions. Physico-chemical parameters of exposed water were measured using standard analytical methods. Blood and liver samples of the exposed fish were collected from each treatment after 5 and 10 days of exposure, and ENA and EROD and GST tests were performed using standard methods. Water quality parameters indicated high levels of chemical oxygen demand, biochemical oxygen demand, total dissolved solid, salinity and conductivity and elevated levels of total phosphate content, nitrate content, heavy metal Cr, Cu and Pb levels in the water collected from the Sites B, M and S compared to tap water (P <0.05). Frequencies of total ENA were significantly higher in the fish exposed to water from the sites B, M and S compared those of the fish exposed to the tap water for 5 and 10 days. Blebbed and notched nuclei contributed mainly to the induction of total ENA than micronuclei and nuclear buds. Total number of nuclear abnormalities was elevated by the 10th day of exposure. Hepatic EROD and GST activities of the fish exposed to polluted water were not significantly different (P >0.05) from those of the fish exposed to tap water, but the enzyme activities were increased in each treatment at 10th day of exposure. Comparison of nuclear abnormalities and hepatic EROD & GST activities of O. niloticus together with physico-chemical analysis revealed that Sites B, M and S of Kelani River are contaminated with organic and inorganic xenobiotics, which may pose harmful cyto-genotoxic impacts on the feral fish populations.Item Assessment of phytochemicals and antifungal effect of Croton aromaticus against postharvest fungal pathogens isolated from tropical fruits(Faculty of Science, University of Kelaniya, Sri Lanka, 2016) Wijesundara, S.A.D.T.L.; Kannangara, S.; Abeywickrama, K.Chemical control using synthetic chemical fungicides is still the most common method of controlling postharvest diseases of fruits. Plant extracts which are rich in antimicrobial secondary metabolites such as terpinoids, alkaloids, saponins and flavonoids could be possible alternatives for synthetic fungicides. Current study was focused on evaluating the antifungal effect of ethanolic extract of Croton aromaticus (Kappettiya) leaves in vitro against mycelial growth and the spore germination of postharvest fungal pathogens isolated from fruits of banana (Colletotrichum musae, Rhizopus sp., Lasiodiplodia theobromae) papaya (Rhizopus stolonifer, Colletotrichum gleosporioides, Lasiodiplodia theobromae) and mango (Alternaria alternata, Pestalotiopsis mangiferae, Lasiodiplodia theobromae). Surface sterilized diseased banana, papaya and mango fruit tissues were cultured on PDA plates in order to obtain pure cultures of possible fungi and they were identified by morphological and microscopic characteristics, using identification keys. Inhibitory effect of the ethanolic extract of C. aromaticus against test pathogens were investigated by well diffusion method using PDA medium, by incorporating crude extract dissolved in DMSO, ranging from 1 mg/ml up to 300 mg/ml concentrations along with the positive (Captan) and negative (DMSO) controls. Significant (P < 0.05) inhibitory effects were exhibited by the ethanolic extract of C. aromaticus leaves against all test pathogens except L. theobromae. The highest mycelial growth and spore germination inhibition of most of the pathogens were observed at 100 mg/ml. The lowest Minimum Inhibitory Concentration of the leaf extract (5 mg/ml) was observed for spore germination inhibition of C. gleosporioides and P. mangiferae. TLC analysis revealed four compounds having Rf values of 0.551, 0.672, 0.810 and 0.913. Phytochemical screening of ethanolic extract revealed the presence of alkaloids, terpenoids, quinones, phytosterols and flavonoids. Current findings indicate the potential use of ethanolic extract of C. aromaticus leaves in controlling banana, papaya and mango postharvest fungal pathogens in vitro.Item A behavioural model to assess risk behaviour of young adults(Faculty of Science, University of Kelaniya, Sri Lanka, 2016) Himasara, T.M.H.; Peter, S.Risk behaviour of young adults have progressively escalated over the past few decades. It generally emerges during adolescence, resulting from a sense of invulnerability, combined with boldness. Therefore, young adults for whom risk taking is a preoccupation of daily life, provide a normative sample for assessing risk behavior. Human risk behaviour has been analyzed mainly based on Western context while studies in the developing country setting is limited. The literature review suggests the need of a tool to evaluate the risk behaviour of young adults in a developing country setting and also the need to establish the relationship between individual characteristics, external stimuli and risk behaviour. The study aims to elicit factors that determine risk behaviour of young adults in Sri Lanka and how these factors can be used to develop risk profiles through a comprehensive model. The behavioural model of the determinants of risk behaviour suggests that this is determined by two individual factors, namely risk propensity and risk perception. Risk propensity was found to be positively related and risk perception was negatively related to risk-taking behaviour. It was further postulated that risk perception partially mediates the effect of propensity to take risk. The model was later extended to analyse the effect of risk on decision-making behaviour in organizational settings where the reconceptualised model describes the joint effect of both dispositional and situational factors on decision making along with organizational and problem characteristics. The reconceptualised model of risk behaviour has been used to form the basis of the model and it has been modified according to the Sri Lankan context by including the individual characteristics and excluding the specific organisational related elements. The individual characteristics influence risk preference while both risk preference and inertia will affect the risk propensity of an individual. The way the problem is framed is influenced by attitudes, beliefs, knowledge and experience. Furthermore, the value systems, norms and cultural ideologies form the social influence which affects the risk perception and finally together with risk propensity affects risk behaviour. The proposed model has been developed through review of literature, and interviews with a number of young adults with a dispersed set of individual characteristics and will be validated in the next phase.Item Biosynthesis of silver and zinc oxide nanoparticles from Plectranthus zeylanicus for the development of antimicrobial formulations(Faculty of Science, University of Kelaniya, Sri Lanka, 2016) de Soyza, W.S.G.; Wijayaratne, W.M.D.G.B.; Napagoda, M.T.; Witharana, S.With the emergence of microbial resistance to currently employed antimicrobial agents, the recent trend is to search for novel antimicrobial substances from nature. The traditional applications of plants and plant based products as well as metals and metalloids suggest the potential of these sources for the discovery of new antimicrobial compounds with diverse chemical structures and novel mechanisms of action. Moreover, it is reasonable to hypothesize that the metal nano-preparations produced from these plant extracts could offer highly potent antimicrobial properties due to the synergistic effect of the plant extract and the metal nanoparticles. Thus the aims of the present investigation are to evaluate the antimicrobial potential of pharmacologically underexplored Plectranthus zeylanicus (Iruveriya), a plant claimed as an antimicrobial remedy in traditional medicine and the green synthesis of silver and zinc oxide nanoparticles as effective herbal disinfectants. The antimicrobial activity of the n-hexane, dichloromethane, ethyl acetate and methanol extracts of P. zeylanicus was determined by disc diffusion and broth microdilution methods against Enterococcus faecalis, Staphylococcus aureus and Staphylococcus saprophyticus. The dichloromethane extract displayed a MIC value of 31.25 μg/mL against S. saprophyticus and S. aureus while a MIC of 250 μg/mL against E. faecalis. Therefore this potent extract was then utilized for the green synthesis of silver and zinc oxide nanoparticles by treating with AgNO3 and ZnSO4 aqueous solutions respectively. The formation of metal nanoparticles was monitored by the measurement of the absorbance of the reaction mixture within the range of 200-600 nm using an ultraviolet-visible spectrophotometer at different time intervals for a period of three days. The silver nano-preparation displayed high absorbance in the range of 240-260 nm and 420- 440 nm and the absorbance of the reaction mixture increased with time. Similarly, the Zinc oxide nano-preparation has shown a high absorbance at 350-370 nm. Products of the green synthesis were evaporated in hot air oven. The scanning electron microscopy was employed to study the morphology of the nanoparticles. The antimicrobial potential of the nano-preparations will be studied in detail for the development of potent and eco-friendly herbal disinfectant/s.Item Camptothecin enhances c-Myc-mediated endoplasmic reticulum stress, leading to cytoprotective autophagy(Faculty of Science, University of Kelaniya, Sri Lanka, 2016) Dilshara, M.G.; Bandara, M.M.K.; Kumara, M.H.S.R.; Molagoda, I.M.N.; Jayasooriya, R.G.P.T.; Kim, G.Y.Camptothecin (CPT) is known to selectively inhibit the nuclear enzyme DNA topoisomerase I which catalyzes the relaxation of negatively supercoiled DNA and thus leads to cell cycle arrest and apoptosis through DNA damages. However, whether CPT induces endoplasmic reticulum (ER) stress and autophagy has not been clearly understood. The LNCaP cells were cultured at 37°C in a 5% CO2-humidified incubator and maintained in RPMI 1640 culture medium containing 10% FBS and antibiotics mixtures. Total RNA was isolated from LNCaP cells using Easy-Blue total RNA extraction kit (iNtRON Biotechnology, Sungnam, Republic of Korea.) according to the manufacturer′s instruction. Total cell extracts were separated on polyacrylamide gels and standard procedures were used to transfer them to the nitrocellulose membranes. Cells were seeded on a 24-well plate at a density of 1 × 105 cells/ml and transfected c-Myc-, JNK-, and eIF2α-specific silencing RNA (siRNA, Santa Cruz Biotechnology) for 24 h. Present study first reported that CPT enhanced DNA-binding activity of c-Myc in LNCaP cells according to electronic mobility shift assay and transient knockdown of c-Myc completely abrogated reactive oxygen species (ROS) generation which was resulting in accumulation of ER stress-regulating proteins such as PERK, eIF2α, ATF4, and CHOP. These observations suggests that CPT-induced c-Myc triggered ER stress along with the PERK-eIF2α-ATF4-CHOP pathway by increasing ROS generation. Moreover, CPT promoted formation of autophagy accompanied by increasing autophagic proteins such as beclin-1 and Atg7. Transfection of eIF2α-targeted siRNA attenuated CPTinduced beclin-1 and Atg7 expression. Treatment with autophagy inhibitors such as 3-methyladenine and bafilomycin A1 downregulated relative cell viability in response to CPT, which indicate that CPT induces ER stress-mediated cytoprotective autophagy. Additionally, CPT significantly induced AMPK phosphorylation as a result of intracellular Ca2+ release. Moreover, CPT phosphorylated JNK and activated DNA-binding activity of AP-1, and knockdown of JNK abolished the expression level of beclin-1 and Atg7, implying that the JNK-AP-1 pathway is a potent mediator on CPT-induced autophagy. Our findings indicate that CPT promotes ROS-mediated ER stress through the PERK-eIF2α-ATF-4-CHOP pathway, which enhances cytoprotective autophagy, resulting from the Ca2+-AMPK pathway and the JNK-AP-1 pathway.Item Categorizing T20 cricket grounds(Faculty of Science, University of Kelaniya, Sri Lanka, 2016) Pathirana, O.D.R.; Mallawa Arachchi, D.K.T20 cricket matches are played by all cricket playing countries. There are more than 80 grounds in various countries on which these games are played. It is hypothesized that some of these grounds favor batsmen while others favor bowlers, or some grounds are high-scoring while others are low-scoring. In this research work, we perform a statistical analysis to determine whether those grounds can be categorized based on the past data. Numerous factors can be considered for the analysis. Main factors we have been considering are the total runs scored in both innings, humidity level, gust, wind, air pressure and the temperature at the grounds when the matches are played. Cluster analysis was used in investigating and determining the number of categories. This study helps identify the behavior of the T20 cricket grounds all over the world and thus enables one to predict the winning possibilities. Data were collected through Cricinfo website from 84 cricket grounds throughout the world. Ward’s method of Hierarchical cluster analysis, which is a major statistical method used in determining the relatively homogeneous clusters, was used. We found that grounds can be clustered into 3 clusters according to the coefficients of the Wards linkage table. When we consider the countries in which these grounds are located, there is no evidence to conclude that grounds in some specific countries are belonging to a particular category. For example there are grounds in India belonging to all three categories. SPSS statistical software was used in this analysis to categorize the grounds. The research work is being carried out to identify how cluster changes with different factors.Item The chromatic number of prime graph of a noncommutative ring Mn×n(Z2)(Faculty of Science, University of Kelaniya, Sri Lanka, 2016) Kolombage, K.A.D.D.B.V.; Wijesiri, G.S.Graph theory is a significant area of Mathematics as its outstanding applications in many fields such as biochemistry, electrical engineering, computer science and operational research. Besides Graph theory, Ring theory is an abstract area in Mathematics. A ring consists of a set equipped with two binary operations that generalize the arithmetic operations of addition (+) and multiplication(∗). Theorems obtained as a result of abstract study of rings can be applied to solve problems arising in number theory, geometry and many other fields. The study of rings with the help of graphs began when a graph of a commutative ring was defined by I. Beck in 1988. Then a new bridge was formed between graph theory and the algebraic concept “ring” noted as prime graph of a ring , denoted by () by B. Satyanarayana, K. Shyam Prasad, and D.Nagaraju in 2010. Later on with the help of existing concepts, K. Patra and S. Kalita investigated the chromatic number of prime graph, (ℤ) of ring ℤ for different values of . Prime graph of a ring is a graph whose vertices are all elements of the ring and any two vertices , of the vertex set are adjacent if and only if ∗ = 0 or ∗ = 0 and ≠ In this paper, we investigate the chromatic number of prime graph of some noncommutative rings ×(ℤ) for different values of n. The chromatic number of prime graph of some commutative rings are formed on the recognition of the conjecture that chromatic number, () and clique number are the same. But for non-commutative rings this is not always the case. Hence, in order to find the chromatic number of prime graph of a non-commutative ring, ×(ℤ), we have looked into MATLAB for a tactical solution.