Browsing by Author "Perera, K."

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Copula-based drought severity-duration-frequency analysis for Anuradhapura and Puttalam in the dry zone of Sri Lanka
(Faculty of Science, University of Kelaniya, Sri Lanka., 2021) Wijesundara, W. R. P. M. S. S.; Perera, K.
Drought is a severe problem in many areas of Sri Lanka, where rainfall amounts are low and extremely high due to climatic changes. To reduce the negative consequences of droughts, it is important to understand the drought characteristics (drought duration and drought severity) and their associations. Therefore, to build a drought severity-duration-frequency (SDF) relationship, a probabilistic technique is proposed using rainfall data from 1996 to 2018 in the two districts Anuradhapura and Puttalam in the dry zone of Sri Lanka. Drought characteristics were defined using 3-month standardized precipitation index (SPI) and Copulas are employed to derive the joint distribution function. Occurrences of 41 droughts from both stations were identified. The derived SDF relationship is a function of marginal distribution functions of drought characteristics linked by a copula. Log-normal distribution and Gamma distribution were identified as the best marginal distribution to represent drought duration and drought severity, respectively, using AIC, BIC and Kolmogorov-Smirnov test. Gaussian copula and Frank copula were identified as the best among the other five copulas based on AIC, BIC and Cramer-Von Mises statistics. Both Log- normal distribution and Gamma distribution along with the Gaussian copula and Frank copula combined to derive the joint distribution of Anuradhapura and Puttalam, respectively. Joint return periods in terms of recurrence intervals were calculated and derived the SDF curves. According to the derived SDF curves, drought severity in Puttalam is greater than those in Anuradhapura for a given recurrence interval and drought duration.
Development of a model for a resource limited setting, to predict the presence of oesophageal varices among newly diagnosed patients with cirrhosis.
(Sri Lanka Medical Association., 2019) Perera, K.; Kodisinghe, S.K.; Ediriweera, D.; Moratuwagama, H.M.D.; Williams, S.; Pathmeswaran, A.; Niriella, M.A.; de Silva, H.J.
INTRODUCTION & OBJECTIVES: In cirrhosis upper-gastrointestinal-endoscopy (UGIE) identifies oesophageal varices (OV). UGIE is unavailable in most resource-limited settings. Therefore, we assessed prediction of presence OV using hematological parameters (HP) and Child-Turcott-Pugh (CTP) class. METHODS: A prospective study was carried out on consecutive, consenting, newly-diagnosed patients with cirrhosis, in the University Medical Unit, Colombo North Teaching Hospital, Ragama, from April 20 I 4-April 2016. All patients had UGIE to evaluate presence and degree of OV, prior to appropriate therapy. HP (FBC with indices using automated analyzer and peripheral blood smear using Leishmann stain) and CTP class were assessed. Linear logistic regression model was developed to predict OV using HP and CTP class. RESULTS: 54-patients with cirrhosis were included [14(26%), 24(44%) and 16(30%) belonged to CTP class A, B and C respectively]. 37 had varices [CTP-A 4/14(26.6%), CTP-B 19/24(79.2%), CTP-C 14/16(87.5%)] on UGIE. Generalized linear model fitting showed decreasing percentage of small platelets (%SP) (P=0.002), CTP-B (P=0.003) and CTP-C (P=0.003) compared to CTP-A had higher probability of having OV. The model predicts the log odds for having OV = - 0.189 - (0.046*%SP) + 2.9 [if CTP-B] + 3.7 [if CTP-C]. Based on ROC analysis, a model value >-0.19 was selected as the cutoff point to predict OV with 89%-sensitivity, 76%-specificity, 89% positive predictive value and 76%-negative predictive value. CONCLUSION: We constructed a model using %SP on peripheral blood smear and CTP class. This model can be used to predict the presence of OV, in newly diagnosed patients with cirrhosis, with high sensitivity and specificity, avoiding the need for initial UGIE.
Effect of capital structure on performance of pubic listed companies in Sri Lanka
(Department of Accountancy, University of Kelaniya, 2015) Perera, K.
This study aims to examine the effect on company capital structure to its performance. First examine the relationship between company capital structures on its performance in order to conclude facts which are effecting to company performance. (Ebaid, 2009) Stated that the relationship of capital structure to company performance is neither positive nor negative. However, (Dawar , 2014) and (Sheikh & Wang, 2013) argued that a negative relationship is exist between capital structure and company performance. Furthermore, (Thomsen & Pedersen, 2000) argue that the positive relationship of capital structure and company performance. Methodology of this research is to collect panel data from fifty companies that are listed in Colombo Stock Exchange (CSE) during the period of 2009 to 2015. Descriptive statistics, Correlation and Regression techniques uses to analyse relationship between Independent and depended variables by process data on regression and correlation techniques. Market to book value ratio (MTBVR) and Return on assets (ROA) uses as dependent variables while using Debt to Equity ratio as independent variable for the analysis. Outcome of this research will be support for investment decisions that are taken by investors. Key words: Sri Lanka, Capital structure, Company performance
High-focus and time-immediate indexicals: A study of Sinhala discourse markers me: ‘this’ and dæn ‘now’
(Journal of Pragmatics, 2015) Perera, K.; Strauss, S.
This article is an investigation of Sinhala demonstrative me:2 and temporal adverb dæn, in their functions as discourse markers. We analyze a corpus of approximately 400 min of naturally occurring, entirely unscripted spoken discourse. The data for this study are taken from televised interviews and political debates, involving a total of 16 speakers (11 male and 5 female). The data were transcribed and Romanized (adapted from Gair, 1998a) to facilitate morpho-syntactic-pragmatic analysis, and allowing for both interlineal glossing and the marking of relevant prosodic features. We identified all instances of the target forms me: and dæn and coded them for their functions as demonstrative/temporal reference markers in addition to their functions as discourse markers. We illustrate the functions of me: ‘this’ as a filler and as a clarification marker, and the functions of dæn ‘now’ as a contrastive marker, a discursive strategy building marker, and a marker of defensiveness to deflect designedly direct face threatening accusations. Our findings indicate that me: ‘this’ and dæn ‘now’ function as discourse management markers, exhibiting remarkable patterns of online interactional and cognitive processes of focus, repair, hesitation, and contrast across the majority of speakers and across all interactional settings in our database.
History and collection of carpets in India, The role of museums in cultural and heritage tourism for sustainable economy in developing countries
(University of Kelaniya, 2013) Perera, K.
Human – Elephant Conflict and Conservation of Elephants in Sri Lanka
(Centre for Asian Studies, University of Kelaniya, Sri Lanka, 2016) Perera, K.
Human – elephant conflict has become a burning question and therefore, it is important to open the public eye to conservation of elephants in Sri Lanka. Most of the human – elephant conflict has occurred due to the fact that the people tend to populate into areas inhabited by elephants. This has caused tremendous death of over 200 elephants annually with a development of growing numbers day by day. At this juncture, it is essential to make awareness from grass root level the importance of conservation to protect the rest of the elephant inhabitants in the country. The Asian elephant is the largest land animal dwelling in the Asia and the elephant has given special place in Asian culture especially in Buddhist and Hindu culture. Not only that they have been used as an icon in flags, logos, coins, official seals and mascots more than any other animal and also illustrated broadly in temple paintings and architecture in Sri Lanka. The fast growing human population has resulted in making use of extensive areas of land for farming and infrastructure development. This has been unfortunately caused in a loss of habitat for elephants, disturbance of their movement patterns and their access to food and water. The effect has been a battle in land use between human and elephants. As human beings it is our responsibility to stop the battle and find out lasting solution to this burning question to protect our vanishing mammals. It is necessary to maintain a database on elephant populations in order to conserve them. It is noted that many parts of the Asian elephant range are captured by human beings for their agricultural work. This has become an important socio-economic and political issue. There should be a sound knowledge of the ecology, behavior, or genetics of elephant populations to conserve our elephants in an effective manner.
A hybrid model for wind speed prediction in Anuradhapura, Sri Lanka
(Faculty of Science, University of Kelaniya, Sri Lanka., 2021) Lenora, K. M.; Abeysundara, S. P.; Perera, K.
Wind energy plays a major role in a sustainable future as a useful, environmentally friendly energy alternative. Wind speed is the most important parameter in the design and implementation of wind energy. This paper aims to define a methodology capable of providing accurate monthly average wind speed predictions in the Anuradhapura region, Sri Lanka. Hybrid forecasting of time series is considered to be a potentially effective alternative compared with the conventional stand-alone forecasting modeling approaches like seasonal autoregressive integrated moving average (SARIMA) and artificial neural network (ANN). In this study, at first, SARIMA and ANN models are used to separately recognize and forecast the linear and nonlinear components of time series, respectively. Then, the study suggests a hybrid approach combining SARIMA and ANN for forecasting wind speed and its forecasting results are compared with the single SARIMA and ANN models. The mean absolute error (MAE), root mean square error (RMSE), and paired sample t-test are used as performance measures. Results obtained by a case study show that the SARIMA-ANN hybrid approach is the most suitable for wind speed forecasting. This approach demonstrates the potential to be applied to wind speed forecasting in other regions of the country.
Intelligent Personality Detection System Using Linguistic Features Based on Social Media Data
(Faculty of Graduate Studies, University of Kelaniya, Sri Lanka, 2016) Sewwandi, D.; Mudiyanselage, O.J.; Perera, K.; Sandaruwan, S.; Nugaliyadde, A.; Thelijjagoda, S.
With the advancement of the technology the transition from forum and blog-based Internet communication among users to social networking sites such as Facebook and Twitter, allow users to create and share content related to different subjects, which expose their activities feelings and opinions. The purpose of this research article is to provide a web application in order to detect one's personality using linguistic feature analysis. The personality of a person is classified according to Eysenck’s Three Factor model including Extrovert - Introvert, Neuroticism - Emotional Stability, and Psychoticism - Tender. The proposed technique is based on ontology based text classification, linguistic feature-vector matrix using LIWC (Linguistic Inquiry and Word Count) features and semantic analysis using supervised machine learning algorithm named Naïve Bayes. The extracted data provides extraordinary information about the personality of a person under human feelings and social interaction. It conveys who the users are and what their qualities are. This is vital for the areas such as HR management systems, R&D Psychologists and all the other API users. Considering HR management sector this would be an advantage in recruiting process, salary increments and providing allowances. R&D Psychologists will gain the advantage of the dynamic ontology to make their research result in a more efficient manner. System will be exposed as an API for universities, sports and social clubs when recruiting individuals to those organizations. According to the test results the proposed system is in an accuracy level of 91% when tested with a real world questionnaire based application. Experiments have been carried out comparing with a real world personality detection questionnaire based system and results demonstrate that the proposed technique can detect the personality of a person with acceptable accuracy and a speed.
Ithin e: kiyanne: An Investigation into Sinhala Discourse Markers
(Department of Linguistics, University of Kelaniya, Sri Lanka, 2016) Perera, K.
Even though discourse markers – such as „well‟ and „now‟ in English – have important functions in speech, they have not figured as an important research area in Sinhala language studies (Fraser 1999; Perera & Strauss 2015). This paper aims to provide a preliminary mapping of the forms and functions of Sinhala discourse markers. The data consist of naturally occurring speech in formal and informal settings including interviews, debates and conversations. These are transcribed and coded for their discursive functions. Using a broad definition of discourse markers as “sequentially dependent elements which bracket units of talk…which are both cataphoric and anaphoric” (Schiffrin 1988, p.31) over ten discourse markers are identified in the speech samples available. These include the markers „mehemayi‟, „ithin‟, „daen‟, „me:‟, „hondayi‟ and „e:kiyanne‟. The saliency of their use depends not only on the speech situation but personal differences as well. These findings illustrate the necessity of further research on Sinhala discourse features in order to understand how Sinhala discourse is structured.
Percentage of small platelets on peripheral blood smear and Child-Turcott-Pugh class can predict the presence of oesophageal varices in newly diagnosed patients with cirrhosis: development of a prediction model for resource limited settings
(BioMed Central, 2019) Perera, K.; Kodisinghe, S.K.; Ediriweera, D.S.; Moratuwagama, D.; Williams, S.; Pathmeswaran, A.; Niriella, M.A.; de Silva, H.J.
BACKGROUND:In cirrhosis upper-gastrointestinal-endoscopy (UGIE) identifies oesophageal varices (OV). UGIE is unavailable in most resource-limited settings. Therefore, we assessed prediction of presence of OV using hematological parameters (HP) and Child-Turcott-Pugh (CTP) class.METHODS:A prospective study was carried out on consecutive, consenting, newly-diagnosed patients with cirrhosis, in the University Medical Unit, Colombo North Teaching Hospital, Ragama, Sri Lanka from April 2014-April 2016. All patients had UGIE to evaluate presence and degree of OV, prior to appropriate therapy. HP (full blood count with indices using automated analyzer and peripheral blood smear using Leishmann stain) and CTP class were assessed on admission. Linear logistic regression model was developed to predict OV using HP and CTP class.RESULTS:54-patients with cirrhosis were included [14(26%), 24(44%) and 16(30%) belonged to CTP class A, B and C respectively]. 37 had varices [CTP-A 4/14(26.6%), CTP-B 19/24(79.2%), CTP-C 14/16(87.5%)] on UGIE. Generalized linear model fitting showed decreasing percentage of small platelets (%SP) (P = 0.002), CTP-B (P = 0.003) and CTP-C (P = 0.003) compared to CTP-A had higher probability of having OV. The model predicts the log odds for having OV = - 0.189 - (0.046*%SP) + 2.9 [if CTP-B] + 3.7 [if CTP-C]. Based on receiver operating characteristic (ROC) analysis, a model value > - 0.19 was selected as the cutoff point to predict OV with 89%-sensitivity, 76%-specificity, 89%-positive predictive value and 76%-negative predictive value.CONCLUSIONS:We constructed a model using %SP on peripheral blood smear and CTP class. This model may be used to predict the presence of OV, in newly diagnosed patients with cirrhosis, with acceptable sensitivity and specificity, to prioritize the patients who deserve early UGIE in limited resource settings
Phonological Awareness and Reading Research: Do all Roads Really Lead to Rome?
(University of Kelaniya, 2007) Perera, K.
Research on reading has been mostly influenced by research findings on reading in English as well as reading in Romance languages. Phonological awareness is now considered the main linguistic factor contributing to reading acquisition (Durgunoglu, Nagy & Hancin-Bhatt 1993). Out of the several phonological phenomena related to reading, a high level of phonemic awareness was long held to be the most important characteristic of a good reader. Research on other alphabets in the last two decades, however, has shown that this is too simplistic a view. Findings of studies on Hebrew, Arabic and Korean have complicated the previously held views on reading acquisition by questioning the bias towards the Roman alphabet in research. The previous decade has also seen a limited amount of research on reading in syllabaries, such as Hindi and Kannada, which has contested the role of phonemic awareness in reading acquisition (Karanth 2002). I have reviewed studies on both alphabets and on syllabaries to show that the type of phonological awareness used for reading differs according to the characteristics of the script and that the first language acquisition of reading affects acquisition of reading in other languages.
Potential impact of predicted sea level rise on carbon sink function of mangrove ecosystems with special reference to Negombo estuary, Sri Lanka
(Global and Planetary Change, 2018) Perera, K.; De Silva, K.; Amarasinghe, M.
Unique location in the land-sea interface makes mangrove ecosystems most vulnerable to the impacts of predicted sea level rise due to increasing anthropogenic CO2 emissions. Among others, carbon sink function of these tropical ecosystems that contribute to reduce rising atmospheric CO2 and temperature, could potentially be affected most. Present study was undertaken to explore the extent of impact of the predicted sea level rise for the region on total organic carbon (TOC) pools of the mangrove ecosystems in Negombo estuary located on the west coast of Sri Lanka. Extents of the coastal inundations under minimum (0.09 m) and maximum (0.88 m) sea level rise scenarios of IPCC for 2100 and an intermediate level of 0.48 m were determined with GIS tools. Estimated total capacity of organic carbon retention by these mangrove areas was 499.45 Mg C ha− 1 of which 84% (418.98 Mg C ha− 1) sequestered in the mangrove soil and 16% (80.56 Mg C ha− 1) in the vegetation. Total extent of land area potentially affected by inundation under lowest sea level rise scenario was 218.9 ha, while it was 476.2 ha under intermediate rise and 696.0 ha with the predicted maximum sea level rise. Estimated rate of loss of carbon sink function due to inundation by the sea level rise of 0.09 m is 6.30 Mg C ha− 1 y− 1 while the intermediate sea level rise indicated a loss of 9.92 Mg C ha− 1 y− 1 and under maximum sea level rise scenario, this loss further increases up to 11.32 Mg C ha− 1 y− 1. Adaptation of mangrove plants to withstand inundation and landward migration along with escalated photosynthetic rates, augmented by changing rainfall patterns and availability of nutrients may contribute to reduce the rate of loss of carbon sink function of these mangrove ecosystems. Predictions over change in carbon sequestration function of mangroves in Negombo estuary reveals that it is not only affected by oceanographic and hydrological alterations associated with sea level rise but also by anthropogenic processes, therefore the impacts are site specific in terms of distribution and magnitude.
Protection of Traditional Knowledge (TK) and Traditional Cultural Expressions (TCEs) of South Asia in Digital Libraries and Museums
(Centre for Asian Studies, University of Kelaniya, 2015) Perera, K.
Traditional medicines and therapies, traditional cultural expressions (TCEs) are used in music, artwork and designs. These are all elements of what is known as traditional knowledge (TK). South Asian countries are rich in TK and TCEs. It has been considered as a treasure and part of the cultural identities. Thus, TK and TCEs give a value to the future wellbeing of local communities and sustainable development of the respective countries. Nevertheless, TK and TCEs have become a part of the human life and added value to their spiritual beliefs and usual the legitimate circle. Therefore, it is important to safeguard TK and TCEs that because of it is vital to sustain not merely the knowledge, but the social and physical environment of which it forms an integral part.
Protection of Traditional Knowledge (TK) and Traditional Cultural Expressions (TCEs) of South Asia in Digital Libraries and Museums
(Centre for Asian Studies, University of Kelaniya, 2015) Perera, K.
Stance-Taking in Sinhala Discourse.
(The Third International Conference on Linguistics in Sri Lanka, ICLSL 2017. Department of Linguistics, University of Kelaniya, Sri Lanka., 2017) Perera, K.
Stance – or stance-taking - is a robust area of study in discourse that has been little applied in Sinhala. Stance is the study of linguistic resources used to express the speaker‟s emotions, attitudes, evaluation of and commitment to propositional content (Biber 2006; Schiffrin 1988; Zubair n.d.). Adverbials, verbs and adjectives marking affect and evidentiality, modals and emphatics have been identified as features showing stance in English (Biber 2006). Given the paucity of work on stance in Sinhala (Zubair n.d.), the main aim of this paper is to provide an overview of the linguistic resources used for stance in Sinhala. Additionally, the paper will also describe selected features of Sinhala that are productively used for stance-marking. Assuming that political discourse is a space for exaggerated instances of stance-taking, televised political debates in Sri Lankan media are used for investigation. Approximately six hours of televised spoken data are transcribed and coded for features that show stance-taking. This study shows that Sinhala uses many of the same features that other languages, including English, use for stance-taking, such as adverbials, affect-laden parts of speech (nouns, verbs, adjectives), and discourse markers. Other than such typical features, Sinhala also uses the focused (or cleft) sentences (eya giye: gedara) productively for stance-taking. Since there are few pragmatic studies of focused sentences in Sinhala (Gair and Paolillo, 1997), this study will describe such uses in political rhetoric. In addition, Sinhala also uses quasi-verbs (puluwan), postpositions (id la), clitics (nisa:m , gijat) and conjunctive participles (ward n y wela) for stance-taking.
සමාජ විශ්වලේඛනයන්හි හුවමාරු සාධාරණත්වය නමැති සංකල්පයෙහි විකසනය පිළිබඳ අධ්‍යයනයක්
(Faculty of Graduate Studies, University of Kelaniya, Sri Lanka, 2016) Perera, K.