PURSE 2004

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Yield enhancement of tube wells by hydrofracturing technique: a casestudy in Sri Lankan hardrocks
(University of Peradeniya Sri Lanka, 2004-11-10) Bandara, A. M. R.; Dharmagunawardhane, H. A.; Amarasinghe, Udeni
Over the last few decades, more than 20,000 tube wells have been constructed in the hardrock terrain of Sri Lanka for drinking water supply purposes. However, about twenty percent of these tube wells have failed due to inadequate yields. The design of a tube well in hard rock areas consists of two main components; a) A comparatively large diameter (165mm to 205mm) vertical drill hole, cased with a PVC casing in the weathered overburden from ground level to the rock, and b) A comparatively smaller diameter (104mm to 165mm) and unlined drill hole in the rock below the casing The depth of tube wells in hard rocks of Sri Lanka usually varies between 30 to about 100m with an average depth of 45m. Groundwater enters the tube well through the discontinuity planes such as joints, faults, lithological contacts or fractures that have been penetrated by the unlined drill hole. The yield of the tube well depends on the amount of groundwater percolating into the borehole through these structural discontinuities which in turn depends on their openness, intensity, interconnection and lateral extent. Filling of weathered materials in these joints and fractures some times reduce the flow of water in to the borehole. The hydro fracturing technique firstly involves isolation of a low yielding discontinuity plane in the rock within the un-lined hole using one or two inflatable packers. Then a very high pressure is applied by pumping water into the isolated joint or fracture zone using a high pressure water pump (600 l/minute at 1OO bars). When the pressure is increased gradually, it abruptly expands the openness of the joints and also develops new interconnections of previously non connected discontinuity planes. This is indicated at the surface as a sudden drop of the pressure in the gauges connected to the high pressure water pump. Under the present study, hydro fracturing technique was applied in 16 low yielding tube wells where the original yield was less than 17 l/minute, In 14 of these wells, the yield was less than 5 l/minute and eight were completely dry. The study revealed that the application of hydro fracturing for enhancing the yield was successful in more than 85% of the tube wells. Yield of the wells had improved to levels that they could be put into use as community water supply wells with hand pumps. Considering the cost of construction of a new tube well to replace an unsuccessful tube well in community water supply programs, it became evident that the vast majority of already drilled and failed tube wells in the country can be rehabilitated with the help of hydro fracturing technique. The present study is the first attempt of this type applied in the hard rock tube wells in Sri Lanka.
The women's ownership of land and property in the Pre-Colonial Period in Sri Lanka (from 3rd century B. C. to 15th century A. D.)
(University of Peradeniya Sri Lanka, 2004-11-10) Chandrika, M.
Many scholars who have analyzed the tenurial system in ancient Sri Lanka have- postulated that males were the owners of land and property. Among them H.W. Codrington, Wilhelm Geiger and M.B. Ariyapala are prominent. But in analyzing the inscriptions and other historical evidence of the pre- colonial era, it is revealed that not only males but females also owned land and property in the past. The objective of this study is to identify women's ownership of land and property in the pre-colonial period. There are several valuable studies about women in ancient Ceylon, but, they mainly examine the social status of women. They have not paid attention to the economic status and ownership of land and property directly. Therefore this study is of very great importance in understanding ancient society and its economy. Details of women's ownership of land and property can be analyzed under the following headings. 1. Ownership, of caves 2. Ownership of monastic establishments 3. Ownership of fields, irrigation tanks, villages etc. In examining details of women's ownerships of land and property, my research has taken into account women's social status. Most of the available evidence illustrates that donations for meritorious or public purposes have been made by women of higher social status, such as, queens, princesses, and mothers, daughters or wives of men of standing. In addition these categories of women also participated in various other economic activities. However, my research will attempt on the basis of the available evidence, to examine land and property rights of women of both upper and lower social status. Apart from donations and grants my research will also attempt to examine the concept of ownership, sale and other forms of alienation of property by women during this period.
Water quality modeling in Kotmale reservoir
(University of Peradeniya Sri Lanka, 2004-11-10) Nandalal, K. D. W.; Abeysinghe, K. G. A. M. C. S.
Kotmale reservoir is the uppermost reservoir in the Mahaweli water resource development scheme in Sri Lanka. Though hydro-energy generation is its prime purpose, it acts as a storage reservoir in the satisfaction of downstream irrigation water requirements, too. Its total storage capacity is about 172x10⁶m³ while the height of the dam is about 87m. The Kotmale reservoir faced several water quality related problems in the recent past. During a severe drought in 1991, the reservoir water level dropped and a thick bloom of Microcystic aeruginosa was observed in the upstream region. This shifted towards the dam due to wind action covering the whole surface of the reservoir This paper presents modeling of water quality in the Kotmale reservoir to predict water quality in it, which enables taking precautionary measures in such situations. The collection of water quality data within a reservoir is very expensive and therefore, the ability to predict water quality, by a model would be very valuable. . A coupled hydrodynamic-water quality model, DYRESM-CAEDYM, was calibrated and validated for the Kotmale reservoir. The component, DYRESM is a one-dimensional hydrodynamic model for predicting the vertical distribution of temperature, salinity and density in lakes and reservoirs. The other component, CAEDYM is a complex ecological model containing process descriptions of primary production, secondary production, nutrient and metal cycling, oxygen dynamics and the movement of sediment. DYRESM-CAEDYM couples these two models, resulting in a powerful tool to investigate the interactions between physics, chemistry and biology in aquatic ecosystems. The model requires a series of input data that include the meteorological conditions (air temperature, relative humidity, wind velocity, solar radiation, rainfall, evaporation), inflow quantity, inflow quality and outflow quantity over the period of simulation in addition to initial vertical distribution of all the simulated state variables. The model DYRESM-CAEDYM was able to predict water quality in the reservoir and released from the reservoir. The model was configured to simulate water level, temperature, salinity, density and 5 water-quality constituents (DO, N0₃, NH₄, PO₄, pH). The model reasonably reproduced the seasonal and spatial patterns of water-temperature, dissolved oxygen, nitrate, ammonia, orthophosphorus and pH. To predict reservoir water quality, the model needs only the inflow water quality, which can be measured easily and inexpensively. If adverse water quality conditions are predicted, precautionary measures that could be taken can be studied with the help of the model. The calibrated model is a useful tool to manage the Kotmale reservoir to avoid adverse water quality conditions in the reservoir as well as supplied from it.
Study of the causative factors for the occurrence of Illukpotha landslide at Kalawana
(University of Peradeniya Sri Lanka, 2004-11-10) Kudahetty, Chamindi; Gunathilake, Jagath
Extremely intense rainfall occurred on 17ᵗʰ May 2003 in the Ratnapura district of Sri Lanka triggered one of the worst natural disaster of the country in the recent past. As a result of the extreme rainfall, landslides and widespread slope failures took place in the hilly areas in the Ratnapura, Kalutara, Matara, Galle and Hambanthota districts. Total of 316 landslide have been reported in the Ratnapura district itself. Among these landslides, IlIukpotha (Pothupitiya Kanda) landslide at Kalawana is the largest landslide occurred in the recent past. It covers approximately one square kilometers area and occurred as a debris flow, taking two paths along the existing valleys. This devastated landslide has been reported to be occurred on 17ᵗʰ May 2003 at 5.45 pm, killing 7 people and destroying 8 houses. This paper deals with the causative factors for occurrence of the Illukpotha landslide, which is located near the 21 km post on the Kalawana-Pothupitiya road in Ratnapura district. The field investigation revealed that this debris flow occurred due to a combination of natural and man-made causes. The extensive precipitation of over 500rnm per day (occurred within 7-8 hours of the day) has become the triggering factor of this landslide, which later converted into a devastative debris flow. IlIukpotha landslide has been initiated due to the saturation of fault zones (N 70°- 80° E and N 40° W) at the crest of the landslide as a result of the extensive infiltration of this rainwater. The underlying geological formation (weathered garnatiferrous charnockitic gneiss with relatively thick clay bands and pegmatite), extensive joint systems (parallel to the above fault systems), fault planes with thin clay seams, slope angle (approximately 35°), and deeply weathered overburden (2-4m thick) were playing a major role. The exposed bed rock along the slope shows the existence of complex folding structures associated with the axial area of the major Potupitiya antiform. General strike of the rocks (succession of charnockitic gneiss, granulitic gneiss, and biotite gneiss) is at East-West direction and except for the landslide initiation area, the whole debris flow is occurred along the dip slope. The landscape features identified on the pre-landslide aerial photographs provide evidences for the occurrence of historical landslide along the slope concerned. More over it was clear that the improper cultivation practices (cultivation of tea introducing horizontal drains in former forest land) on the steep hill slopes at this area, have further accelerated the infiltration rate. Therefore, it could be concluded that the fundamental causative factors for occurrence of the Illukpotha landslide were; continuous excessive precipitation within a short period of the day, existence of the faults, and prominent rectangular joint pattern, deeply weathered thick overburden and the change of land use from forest to tea cultivation.
A study on cardiotoxin of Sri Lankan Cobra
(University of Peradeniya Sri Lanka, 2004-11-10) Ranasinghe, J. G. S.; Suzuki, M.; Athauda, S. B. P.; Perera, P. A. J.; Moriyama, A.
Sri Lanka has the highest fatality rate of snakebites in the world. The cobra (𝘕𝘢𝘫𝘢 𝘯𝘢𝘫𝘢 𝘯𝘢𝘫𝘢) is one the most dangerous species in the Indian subcontinent. Anti venom serum (AVS) is the only effective therapy available for treatment of snake bite. Anaphylaxis can be fatal unless emergency treatment is given. At this juncture, it is worthwhile to investigate the composition of the toxins of Sri Lankan cobra and find out their homogeneity to Indian species. In this study, venom was collected from captured cobras reared at the reptile facility in the Faculty of Medicine, University of Peradeniya. Crude venom was purified by chromatographic met;hods and the purified product was subjected to protein sequencing. The cardiotoxin of Sri Lankan cobra which is responsible for tissue reactions and haematological changes after envenomation was analysed. In order to clarify the structural relationship among them, amino acid sequence of cardiotoxins determined in this study were compared with those of cardiotoxins already reported in other cobra species. The amino acid sequences of the cardiotoxin, present in the Sri Lankan cobra is different from other Asian cobras. It is much closer to 𝘕𝘢𝘫𝘢 𝘯𝘢𝘫𝘢 𝘰𝘹𝘪𝘢𝘯𝘢. This study supports the view that there are genetical differences between the Sri Lankan and Indian cobra species. It is beneficial to analyse the major toxins of our endogenous snakes and produce anti venom specific to our species in Sri Lanka, thereby helping to reduce the high fatality due to snakebite.
Super-elevation of flow in channels of nonlinear alignment
(University of Peradeniya Sri Lanka, 2004-11-10) Wijethunga, J. J.
The presence of curves or bends in alignment is unavoidable in the design of open channels. However, the flow at a bend is quite complicated due to the presence of spiral currents,cross-waves and also the super-elevation of the water surface. The difficulties in the designof channels of nonlinear alignment often arise due to the paucity of information on the reliabilityof the theoretical formulae available in the literature for the estimation of the super- elevationof flow at bends. In this backdrop, the primary objectives of the present study are: i) to improve our understanding of the flow behaviour at bends, and, ii) to examine the reliabilityof the theoretical formulae mentioned above, through an experimental investigation of the flow in channels of nonlinear alignment over a range of the relevant dimensionless parameters. The experimental work was carried out in a 6 m long masonry open channel consisting of a 60°- bend with a radius of curvature of 0.75 m. The original width and the height of the channel were 310 mm and 350 mm, respectively, whilst the channel slope was 0.02. Subsequently, the width, the height and the slope of the channel were changed to obtain measurements over a wider range of the relevant dimensionless parameters. Further, the velocity measurements were made using a 20 mm diameter propeller meter equipped with a digital counter. The measurements have been compared with the following semi-empirical formulae that are available to estimate the super-elevation. In these formulae, 𝘣 is the width of the channel; 𝘨 is the acceleration due to gravity; 𝘳 is the radius of curvature of the bend with the subscripts 𝘤, 𝘪 and 𝘰 denoting centre, inner and outer, respectively; 𝘝 is the flow velocity; and Δ𝘏 is the super-elevation of the flow. [The abstract includes mathematical functions and symbols.] The results indicate that the measured values of Δ𝘏 are closer to equations (1) and (2), whilst equation (3) under-predicts the measurements by about 50%. Therefore, it appears that equations(I) and (2) are more reliable than equation (3) in estimating the super-elevation. The way in Δ𝘏/𝘣 varies with 𝘥/𝘣 (𝘥 is the water depth) for different values of 𝘳/𝘣 has also been examined, and it appears that the general trend is for Δ𝘏/𝘣 to increase with increase of 𝘥/𝘣.
TCP vs UDP for distributed real-time applications: a practical approach
(University of Peradeniya Sri Lanka, 2004-11-10) Vijayananda, T.; Samaranayake, L.; Alahakoon, S.
Vast attentions have been paid both in the industry and academia on IP based Ethernet networks for distributed real-time applications mainly due to cost, compatibility and maintainability reasons. The controller in a distributed real-time system has access to the network through the network interface card of the computer in which it is implemented. However, the object to be controlled (Brushless DC motor (BLDC) in this case) must be provided with network connectivity by external means, which interfaces the object to the network. Development of such an Ethernet Ready Sensor Actuator (ERSA) module at a locally affordable cost using local engineering skills and technology is presented in the first half of the paper. The completed ERSA hardware module is capable of completing one analog to digital conversion of the sensor measurement and a digital to analog conversion of the received control input needed for a single actuation cycle within 1 ms. Further it supports changing sampling frequency, type of protocol, actuating mode i.e., time triggered or event triggered. In the second half, the ERSA module is used in a 10/100 Mbps Switched Ethernet network to control the speed of a 3000rpm inverter fed BIDe motor. Connection oriented, reliable Transport Control Protocol (TCP) and connectionless best effort User Datagram Protocol (UDP) have been used in the network layer. A comparative study is carried out on TCP and UDP for artificial variable network traffic in the distributed control loop with the intention of finding the better network layer protocol for distributed real-time applications. The experimental results show that under lower network traffic (up to about 70% network utilization), both protocols behave the same. However, when it reaches 90%, TCP starts deteriorating. But UDP remains unchanged. This is contradictory to the expected performance based on the construction of the two protocols. The possible reason is that the time consumed on flow control mechanisms in TCP becomes a burden under heavy utilization. Since UDP uses no such mechanism, its performance remains unchanged. This aspect needs further attention in the future.
"Teaching" a foreign culture: the challenge
(University of Peradeniya Sri Lanka, 2004-11-10) Herat, K.
It is a known fact that language and culture cannot be dissociated and therefore, the of a foreign language needs to focus also on the "study" of the foreign culture, that is, of elements that compose this foreign culture. The issue raised in this paper is precisely that the 𝘥𝘪𝘧𝘧𝘪𝘤𝘶𝘭𝘵𝘺 of "teaching" elements of French culture to Sri Lankan students of French . main obstacles that bring about this difficulty can be identified: • The distance between the two countries makes the cultural realities themselves difficult to conceptualize. • The contact with the French culture is only through video, written documents and the teachers of French, many of who too have not experienced French culture . • A French community outside of the capital city is almost non-existent. Students therefore do not have the opportunity of interacting with French people. As part of our research we asked 50 teachers of French if they included the study of French culture in their teaching programme. We also asked them what methodology they used in transmitting or "teaching" French culture to their students. The results obtained varied in the following manner: • 80% of teachers of French in the State Sector schools said they neglected this aspect since French culture was 'alien' to them. They had never '𝘭𝘪𝘷𝘦𝘥' or 𝘦𝘹𝘱𝘦𝘳𝘪𝘦𝘯𝘤𝘦𝘥 it. • 10% said they made reference to French culture in their classes since they had been to France for short-term summer training programmes and were able to explain a minimum of cultural elements, They supplemented their knowledge through reading and by listening to programmes on French television at the Alliance Francaise. • Explanations were based on the knowledge acquired by the teacher through reading and this information was given to the students. • 65% -70% of teachers were faced with the difficulty of selecting passages for study in the classroom. They were unable to explain cultural elements when they figured in the text and were therefore hesitant to use these documents in class. Culture cannot be dissociated from language. How then can the problem of "teaching" elements of French culture to Sri Lankan students of French be addressed?
Textual criticism as practiced by early Sinhalese scholars
(University of Peradeniya Sri Lanka, 2004-11-10) Dissanayake, K. S.
The scientific process of emending manuscripts is known as Textual Criticism'. The method has been practiced in both Eastern and Western literatures from the early times. However, the term Textual Criticism' was first used in the mid 19th century. In this research my attempt is to show that Sri Lankan and Indian scholars practiced 'Textual Criticism' as a technical activity and it can be compared with the modem method mentioned above. The Buddhist tradition of Textual Criticism' is an important branch of the Indian tradition. The 𝘚𝘶𝘵𝘵𝘢𝘱𝘪𝘵𝘢𝘬𝘢 contains seven-fold process of analyzing 𝘋𝘩𝘢𝘮𝘮𝘢. In the process of studying 𝘈𝘣𝘩𝘪𝘥𝘩𝘢𝘮𝘮𝘢, the method adopted is described in five steps. The three 𝘴𝘢𝘯𝘨𝘢𝘺𝘢𝘯𝘢𝘴 in Tripitaka held in India took a considerable part in re-constructing the original words of the Buddha. What had taken place at these 𝘴𝘢𝘯𝘨𝘢𝘺𝘢𝘯𝘢𝘴 was a laborious process of the discussion of the texts orally transmitted and arriving at a consensus with a view to establishing an authoritative text. The history of text editing in Sri Lanka extends as far back as the 151 century B.C. That was the instance of texts transmitted hither to orally being written down at 𝘈𝘭𝘶𝘷𝘪𝘩𝘪𝘪𝘳𝘢. This is not a mere copying but also involved reading and emendation. My main task here is to probe into the editorial actions of Buddhaghosa in the translation of Sinhalese commentaries into Pali. His task was not a mere translation, but to edit the Sinhalese works according to the 𝘗𝘢𝘭𝘪 '𝘵𝘢𝘯𝘵𝘪𝘺𝘢𝘯𝘶𝘤𝘤𝘢𝘷𝘪𝘬𝘢𝘯 𝘣𝘩𝘢𝘴𝘢𝘯'). The procedure u applied by him, as described himself in his works is as follows: by taking the substance of the & old commentaries (𝘱𝘰𝘳𝘢𝘯𝘢𝘵𝘵𝘩𝘢𝘬𝘢𝘵𝘩𝘢𝘯𝘢𝘮 𝘴𝘢𝘳𝘢𝘮 𝘢𝘥𝘢𝘺𝘢), including the opinion of the elders (𝘢𝘯𝘵𝘰𝘨𝘢𝘥𝘩𝘢𝘵𝘩𝘦𝘳𝘢𝘷𝘢𝘥𝘢𝘯 𝘺𝘶𝘵𝘵𝘢𝘮𝘢𝘵𝘵𝘩𝘢𝘯 𝘢𝘱𝘢𝘳𝘪𝘤𝘤𝘢𝘫𝘢𝘯𝘵𝘰), exceeding any error of transcription (𝘱𝘢𝘮𝘢𝘥𝘢𝘭𝘦𝘬𝘩𝘢𝘯 𝘷𝘢𝘫𝘫𝘢𝘪𝘵𝘷𝘢𝘯𝘢), condensing detailed accounts (𝘷𝘪𝘵𝘵𝘩𝘢𝘳𝘢𝘮𝘢𝘨𝘨𝘢𝘯 𝘤𝘢 𝘴𝘢𝘮𝘢𝘴𝘢𝘺𝘪𝘵𝘷𝘢), including authoritative decisions (𝘷𝘪𝘯𝘪𝘤𝘤𝘢𝘺𝘢𝘯 𝘴𝘢𝘣𝘣𝘢𝘮𝘢𝘴𝘦𝘴𝘢𝘺𝘪𝘵𝘷𝘢), without overstepping any Pali idioms (𝘵𝘢𝘯𝘵𝘪𝘬𝘬𝘢𝘮𝘢𝘯 𝘬𝘪𝘯𝘯𝘤𝘪 𝘢𝘷𝘰𝘬𝘬𝘢𝘮𝘪𝘵𝘷𝘢). Whenever the commentator had to give his own opinion on any point of suspect, he did not fail to mention that the views are his own (𝘢𝘺𝘢𝘮 𝘱𝘢𝘯𝘢 𝘮𝘦 𝘢𝘵𝘵𝘢𝘯𝘰 𝘮𝘢𝘵𝘪). At the points that he cannot give a proper decision, Buddhagosha records the whole incident and delegates the judgment to the reader (𝘺𝘢𝘩𝘵𝘢 𝘸𝘢 𝘵𝘢𝘩𝘵𝘢 𝘸𝘢 𝘩𝘰𝘵𝘶). This method of analyzing fact is known as 𝘔𝘢𝘩𝘢𝘱𝘢𝘥𝘦𝘴𝘢 in early Buddhism. On many occasions in commenting he consulted manuscript of various schools, and faithfully recorded the variant readings that he found in the texts. His main effort was to arrive at the basic text with supreme authority. As the Encyclopaedia Britannica points out, the method or the critical process applied in restoring text has been resolved into three stages, namely (1) Critical Recension, (2) Examination and (3) Emendation. Emendation is further linked with conjecture. 1 shall take into consideration these modem methods and try to investigate the achievement of Buddhaghosa in his editorial works of translation Sinhala texts into Pali.
Traditional knowledge system of Panama Village in Eastern Sri Lanka
(University of Peradeniya Sri Lanka, 2004-11-10) Wickramaratne, S. N.
Traditional knowledge is also referred to as indigenous knowledge, indigenous ecological knowledge and traditional ecological knowledge. Noted author, Barry Lopez defines it as "vast and particular knowledge . . . garnered from hundreds of years of . . . patients interrogation of the landscape." Anthropologist Ellen Bielawski defines it as "practical strategies; what's worked and what hasn't It is not a static one but is both cumulative and dynamic." Today the value of traditional knowledge is increasingly understood and the Rio de Ianeiro Earth Summit (1992) recognizes the importance of traditional knowledge to environmental management and development. Even the Ministry of Environment and Natural resources of Sri Lanka has drafted a national policy on indigenous knowledge. In Sri Lanka too there is a vast body of traditional knowledge and this paper is based on a study carried out in 2003 following the 'rapid rural appraisal' approach, on the knowledge system of Panama Village situated 16krn south of Pottuvil and Arugam Bay in eastern Sri Lanka. This village is one of several places in the island where the traditional ways still persists. The agrarian community of people (5000) of the isolated village 𝘗𝘢𝘯𝘢𝘮𝘢 possesses a time-tested knowledge base that is intimately linked with nature. Their agricultural calendar including pest control, synchronized with the annual climatic cycle is based on accumulated environmental knowledge. Rice farming and 𝘤𝘩𝘦𝘯𝘢 practice as well as diary farming are harmoniously done. Seafood and forest products such as honey and wild fruits supplement this agriculture. This has given the village self-sufficiency in food. The indigenous medicine, handicrafts and the traditional event '𝘢𝘯𝘬𝘦𝘭𝘪𝘺𝘢' are parts of the traditional knowledge system. A unique feature of this knowledge is that it is entwined with local beliefs that reflect reverence for nature in this isolated, harsh environment. The importance of the traditional knowledge system of Panama is that, it has helped the people of this village to the sustainable use of the area's natural resource base for centuries.
Trichoderma harzianum as a biocontrol agent for 𝘗𝘺𝘵𝘩𝘪𝘶𝘮 𝘢𝘱𝘩𝘢𝘯𝘪𝘥𝘦𝘳𝘮𝘢𝘵𝘶𝘮, a causal organism of damping-off of tomato
(University of Peradeniya Sri Lanka, 2004-11-10) Athukorala, A. D. S. N. P.; Abeysekara, C. L.
Soil-borne fungal diseases in plants cause a severe reduction in the quality and quantity of plant products in agricultural lands. Damping-off disease, which occurs mainly due to the attack of 𝘗𝘺𝘵𝘩𝘪𝘶𝘮 sp., is one such disease affecting most species of crop plants, specially the Solanaceae crops including tomato. Methods of prevention and disease control include the use of fungicides, reduction in seedling density and biological control. 𝘛𝘳𝘪𝘤𝘩𝘰𝘥𝘦𝘳𝘮𝘢, a soil-borne fungus, has been found to be a successful biocontrol agent against a number of soil-borne pathogenic fungi over a period of years. 𝘛𝘳𝘪𝘤𝘩𝘰𝘥𝘦𝘳𝘮𝘢 sp. was isolated from garden soil mixed with decomposing plant material, by the dilution plate method on Potato Dextrose Agar medium (PDA). Based on colony, morphological characteristics and growth rate measurements on 2% Malt Extract Agar (MEA), the species was identified as 𝘛𝘳𝘪𝘤𝘩𝘰𝘥𝘦𝘳𝘮𝘢 𝘩𝘢𝘳𝘻𝘪𝘢𝘯𝘶𝘮. The causal organism was isolated on water agar from root tips of diseased seedlings, collected from a seedling bed of tomato (cultivar: Thilina, V/2/3/K.U.N/OO3). Based on colony and morphological characteristics, the fungus was identified as 𝘗𝘺𝘵𝘩𝘪𝘶𝘮 𝘢𝘱𝘩𝘢𝘯𝘪𝘥𝘦𝘳𝘮𝘢𝘵𝘶𝘮. The biocontrol ability of 𝘛𝘳𝘪𝘤𝘩𝘰𝘥𝘦𝘳𝘮𝘢 𝘩𝘢𝘳𝘻𝘪𝘢𝘯𝘶𝘮 against 𝘗𝘺𝘵𝘩𝘪𝘶𝘮 𝘢𝘱𝘩𝘢𝘯𝘪𝘥𝘦𝘳𝘮𝘢𝘵𝘶𝘮 was tested in comparison to 0.02% Captan [1,2,3,6-Tetrahydro-N-(trichloromethylthio) phthalimide 3a,4,7,7a-Tetrahydro-2-[(trichloromethyl)thio]-lH-isoindole-1,3(2H)-dione], a recommended contact fungicide to control the disease. Linear growth measurements of 𝘗. 𝘢𝘱𝘩𝘢𝘯𝘪𝘥𝘦𝘳𝘮𝘢𝘵𝘶𝘮 on PDA plates were taken in the presence of treatments (𝘛. 𝘩𝘢𝘳𝘻𝘭𝘢𝘯𝘶𝘮 or fungicide). The inhibition in growth of 𝘗. 𝘢𝘱𝘩𝘢𝘯𝘪𝘥𝘦𝘳𝘮𝘢𝘵𝘶𝘮 was significant (P = 0.05 level) in 𝘛. 𝘩𝘢𝘳𝘻𝘪𝘢𝘯𝘶𝘮 treated plates compared to the fungicide treatment and the control. In vivo effect of 𝘛. 𝘩𝘢𝘳𝘻𝘪𝘢𝘯𝘶𝘮 against damping off development was tested using tomato plants in a moisture chamber at room temperature (27 ± 1°C). The treatments were addition of a spore suspension (106) of 𝘛. 𝘩𝘢𝘳𝘻𝘪𝘢𝘯𝘶𝘮, fungicide (0.02%) and reducing the number of seeds planted. The number of diseased seedlings was counted 10 days and 14 days after planting and percentage disease incidence was calculated. There was a 88.8% reduction in disease incidence by 𝘛. 𝘩𝘢𝘳𝘻𝘪𝘢𝘯𝘶𝘮; which was significant at P = 0.05 level. Treatment with 𝘛. 𝘩𝘢𝘳𝘻𝘪𝘢𝘯𝘶𝘮 was 30.6% more effective than the fungicide used (Captan) and 18.4% more effective than reduced seedling density. Results obtained from the current study showed that damping-off disease of tomato caused by 𝘗𝘺𝘵𝘩𝘪𝘶𝘮 𝘢𝘱𝘩𝘢𝘯𝘪𝘥𝘦𝘳𝘮𝘢𝘵𝘶𝘮 can be significantly reduced by the biocontrol agent 𝘛𝘳𝘪𝘤𝘩𝘰𝘥𝘦𝘳𝘮𝘢 𝘩𝘢𝘳𝘻𝘪𝘢𝘯𝘶𝘮.
Unilateral absence of the external Jagular Vein -a rare anomaly
(University of Peradeniya Sri Lanka, 2004-11-10) Hewapathirana, T. N.; Batagalla, J.; Dharmakeerthi, W.; Nanayakkara, C. D.
The superficial veins of the neck, especially the external jugular vein (EJV) are increasingly being used for establishing reliable central venous access for haemodynamic monitoring and long-term intravenous therapies. As these veins show numerous variations their exploration is important to gain a better anatomic knowledge of the neck. The EJV, the most important vein providing blood return from the face and scalp is formed in the substance of the parotid gland at the level of the angle of the mandible by the union of the posterior auricular vein and the posterior division of the retromandibular vein. It descends vertically in the superficial fascia to mid clavicle undercover of the platysma to terminatein the subclavian vein. During student anatomic dissections of 36 formalin preserved adult cadavers (22 males and 14 females) in the age range of 26 to 87 years a study was initiated to investigate into the numerous variations of the superficial veins. Evaluation of 72 neck halves for variations of the EJV revealed its presence in 71 cases (98.6%) but it was completely absent on the right side of one male cadaver. In this poster we present the arrangement of superficial neck veins in the absence of the EJV. It was noted that the tributaries forming the EJV in the region of the parotid gland, namely the posterior auricular vein and the posterior division of the retromandibular vein were joining the common facial vein (FV) to drain into the internal jugular vein (IN). It was also observed that the tributaries of the EN near its termination, the suprascapular, transverse cervical and the anterior jugular veins were directly flowing into the subclavian vein. Both the FV and the IN were unusually larger than their counterparts on the opposite side and the measurement of diameters of these vessels using a high precision digital caliper revealed the diameters of the FV on the right and left sides to be 7.27 mm and 5.59 mm respectively 'and the IJV to be 14.38 mm and 8.38 mm respectively. The anomalous patterns found in our study could be explained in terms of the regression and retention of various parts of the fetal veins found during early development. As this anomaly is not documented in the literature previously it may be considered a rare variant of the EN. A good knowledge of the variations associated with the EJV will be useful to the clinician as this vein is increasingly being used for central venous catheterization
Clinical outcome of habit control and submucosal Injection of long acting steroid in the management of oral submucous fibrosis - a follow up study
(University of Peradeniya, 2004-11-10) Ariyawardana, A.; Nawagamuwa, T.; Ranasinghe, A. W.; Sitheeque, M. A. M.; Vithanaarachchi, N.
The aim of this study was to assess the effectiveness of intra-lesional injection of methyl prednisolone and habit control in the management of Oral Submucous Fibrosis (OSMF). The sample consisted of 43 patients (male = 28, female = 15) who attended the Oral Medicine Clinic, Faculty of Dental Sciences, University of Peradeniya from January 2001 to December 2003. The diagnosis of OSMF was based on the criteria recommended at the workshop on oral mucosal lesions associated with betel quid, arecanut and tobacco chewing habits held in Kuala Lumpur, Malaysia (1997). Patients were divided into the following groups depending on the unaided degree of mouth opening. Group A: maximum mouth opening ≥ 20 mm n=38 Group B: maximum mouth opening 11-19 mm n= 4 Group C: maximum mouth opening ≤10 mm n = 1 Submucosal injection of methyl-prednisolone (20 mg = 0.5 rnI) was given to predetermined areas of buccal mucosae of each side for all the patients once a month for 5 consecutive months. Maximum unaided mouth opening was measured using the same measuring device after one month of each injection. All the patients were informed about the causal relationship of the betel chewing habit to OSMF and the hazardous effects if the habit was continued. They were also instructed to quit betel chewing, smoking and alcohol habits. Men outnumbered women (1.8: 1) though equal numbers were observed in age groups 15-24, 55-64 and >64. All subjects chewed betel with arecanut. Three subjects had stopped their habit before attending the hospital mainly due to the intolerable burning sensation in the mouth. At the end of the 6 month follow up period, a total of 37 cases (86%) from all three groups showed significant improvements in their mouth opening (Z=-5.283, P
The role of tea stem saponins in the resistance of tea to attach by 𝘟𝘺𝘭𝘦𝘣𝘰𝘳𝘶𝘴 𝘍𝘰𝘳𝘯𝘪𝘤𝘢𝘵𝘶𝘴
(University of Peradeniya Sri Lanka, 2004-11-10) Karunaratne, W. Subodhi; Jayasinghe, Sarath B.; Kumar, V.; Wimalasiri, K. M. Swarna
The resistance of tea to attack by the Shot Hole Borer, 𝘟𝘺𝘭𝘦𝘣𝘰𝘳𝘶𝘴 𝘍𝘰𝘳𝘯𝘪𝘤𝘢𝘵𝘶𝘴 has been ascribed to the higher content of saponins in their stems. It was suggested that tea stem saponins complex with lea stem sterols making the sterols no longer available to the beetle, which is unable to obtain the sterols required for the production of moulting hormone. The saponin content of stems from a resistant and susceptible clone of lea were studied and it was confirmed that the saponin content of the resistant clone was significantly higher. The beetle was grown in different artificial media, with and without tea stern saponins and media devoid of the steroid source, yeast to determine the effect of saponins and the absence of steroid on the hectic life cycle. No significant differences compared with control were observed even after ten generations in the beetle life cycle when grown in artificial media not containing a steroid source. The role of the saponins in resistance, if any. could not therefore be by depriving the beetle of steroid. It is likely that the beetle's requirement of sterol is met by ergosterol present in the fungus, 𝘔𝘰𝘯𝘢𝘤𝘳𝘰𝘴𝘱𝘰𝘳𝘪𝘶𝘮 𝘢𝘮𝘣𝘳𝘰𝘴𝘪𝘶𝘮 which is associated with the beetle in its life cycle. Although no significant differences were found between the life cycle of beetles growing in control and those in artificial media containing saponins, liquid culture media studies showed that saponins were toxic to the fungus, 𝘔. 𝘢𝘮𝘣𝘳𝘰𝘴𝘪𝘶𝘮. The growth of the fungus in terms of mycelial weight was significantly reduced although no effects were observed on the sporulation of the fungus. It is concluded that, although saponins do not provide resistance to tea clones oy complexing with tea steroids, they may contribute to resistance by preventing the healthy growth of fungal mycelia, required for larval growth.
A timetablesystem based on graph coloring
(University of Peradeniya Sri Lanka, 2004-11-10) Wickramasekara, M. I. U.; Perera, A. A. I.
Graph theory is an important branch of Applied Mathematics with numerous applications to solve practical problems in Electrical networks, Circuit layout, Data structures, Operations research and Social sciences. Graph coloring is one of the most important areas of graph theory. The chromatic coloring problems of the graph is related to many problems of matching such as the assignment of crews to work centers, time tabling problems of crews, exam scheduling etc. This paper presents graph coloring and room allocation algorithms and shows how these two algorithms can be combined together to provide a basis of a flexible and widely applicable time tabling system. Such problems are formulated. in a mathematical model and the solutions are obtained by using a computer program in Visual Basic language. How several common timetabling features can be handled within the system is also discussed in detail.
Chronic Renal Failure in the Medawachchiya-Padaviya Areas: A Geo-Environmental Study
(University of Peradeniya, 2004-11-10) Ileperuma, O. A.; Dharmagunawardhane, H. A.; Herath, K. R. P. K.
While the etiology of the chronic renal failure in the Medawachchiya-Padaviya areas still remains a mystery, some results on the geo-environmental factors of the region reveal some significant findings. A chance discovery made during field studies was that people exclusively use aluminium utensils and that holes were observed in these utensils after continuous use. Water used by these people mostly come from dug wells and they generally have high fluoride content in the range of 1.00-4.00 ppm with a median of around 1.3 ppm. Fluoridation of drinking water is in the midst of a controversy owing to studies, which have shown a direct link between aluminium and fluoride to Alzheimer like symptoms in experimental animals. A cocktail of aluminium and fluoride laced water given to rats showed that the animals develop Alzheimer like symptoms but their premature deaths were attributed to kidney failure. The ability of the aluminofluoride complexes to penetrate the blood-brain barrier has been forwarded as a possible explanation for this observation. The present study aims to establish any relationship between fluoride, aluminium utensils and chronic renal failure. In this study pieces of aluminium from a used aluminium pot were treated with fluoride water containing at different levels of 1.0-4.0 ppm. After two days of standing at room temperature, the amount of aluminium leached was measured by a colorimetric technique (aluminon reagent) to determine uncomplexed aluminium and atomic absorption spectrophotometry to determine total aluminium. The amount of aluminium leached out in the absence of fluoride was 0.43 ppm while in 1 ppm fluoride medium the free aluminium observed was 3.00 ppm where the total aluminium was 11.87 ppm. Surprisingly, the amount of aluminium leached was lower at hgher concentrations of aluminium. This observation is similar to the results from studies on rats where lower concentrations of aluminum fluoride produced more toxic effects than at higher concentrations. In the presence of an acidic medium, using 2g/l of tartaric acid and I ppm fluoride, the aluminium leached was around 56 ppm which is a five-fold increase in the dissolution of aluminium. This experiment was performed owing to the widespread use of acidic ingredients like tomatoes, tamarind, vinegar and limejuice during cooking in aluminium pots. Aluminium leaching under high fluoride stress and acidic spices results in the formation of aluminofluoride complexes such as AlF63., which are soluble and penetrates the blood brain barrier. This stable AlF₆³⁻. complex has an overall formation constant of 6.9 x 10¹⁹ . The observation of both dental and skeletal fluorosis amongst the affected patients gives further credence to the hypothesis that aluminium and fluoride in combination could be a possible reason for the occurrence of chronic renal failure in areas with high fluoride content in water.
CIM System Expansion With Minimal Changes to Installed Source Code
(University of Peradeniya, 2004-11-10) Dewasurendra, S. D.
The need to upgrade the CIM (Computer Integrated Manufacturing) Systems to provide increased capability in the face of rapid change in product/process specifications has been identified: integration of mechatronic devices such as CNC machines, robot manipulators, automatic assembly systems is a major effort in manufacturing and automation systems, particularly in the face of an increasing demand for these systems to be agile. Agility implies the capability of responding to production changes, both in volume and variety, rapidly, effectively and reliably with low cost. Due to differences in user interfaces to these equipment significant recoding is often needed in response to changes required in production systems. The code that can run into thick volumes has to be verified before installation. Hence, modifying the installed control software to facilitate extension or modification of the system to suit current needs is not straight forward. The present problem is to provide a suitable framework which would facilitate such extension and improvement. In the proposed approach, we wrap already installed software modules in CGI script thus making it possible for them to cooperate with new control modules. The system control is designed and specified using the Universal Modelling Language (UML). In order to provide re-configurability we define port structures between each pair of communicating classes. Verification is localised by having to verify a module using only the information contained in the ports to which it is connected.
Clinical Aspects of Oral Lichen Planus in a Group of Sri Lankan Patients
(University of Peradeniya, 2004-11-10) Ariyawardana, A.; Seneviratne, C. J.; Sitheeque, M. A. M.; Ranasinghe, A. W.
The aim of this study was to determine clinical characteristics of oral lichen planus (OLP) in a group of Sri Lankan patients who attended the Dental Hospital for treatment. A total of 104 patients with oral lichen planus who attended the Oral Medicine clinic, Faculty of Dental Sciences, during the period from January 2001 to December 2003 were included in the study. Information pertaining to demographic data, duration of oral lesions and existence of skin lesions were obtained and site and types of the lesions were recorded. Patients with the history of current usage of drugs known to cause lichenoid reactions and with amalgam fillings associated with lesions were excluded from the study. Incisional biopsies were taken from lesions of all the patients in order to confirm the diagnosis. The mean age of the study population at the time of presentation was 45 years and the highest number of cases was found in the age group of 45-55 years (χ²=20.26, df=5, P=O.OO1). Females outnumbered males (1.5: 1). The mean period of experience of the disease before seeking treatment was 4.4 months. 16.3% (n=17) had no symptoms and the rest had feelings of roughness, burning sensation at meal times and spontaneous mucosal burning. There was no gender difference with respect to symptoms (χ²=3.323, df=3, P=O.344). Fourteen patients (13.5%) had shown skin lesions. Six clinical types were identified namely reticular (58.7%), papular (1.9%), plaque like (3.8%), atrophic (2.9%), ulcerative or erosive (6.7%) and lesions with combination of different morphological variants (26%). There was no gender difference with regards to the different clinical types (χ²=5.769, df=5, P=O.329). All patients with atrophic and erosive/ulcerative types had burning sensation as the main symptom. Forty-eight out of 61 patients (78.6%) with reticular type and 19 patients out of 27 (70.3%) with mixed types had burning sensation at meal times. Common sites of affliction were left buccal mucosa (76.9%), right buccal mucosa (75%), dorsum of the tongue (16.3%), lower vermilion border (10.6%) and gingiva (7.7%). The most frequent mucosal combination was the left and right buccal mucosa affecting 66 patients (63.5%). Eighty-seven patients (83.6%) needed therapeutic management and the mainstay of treatment was corticosteroids. Only eight patients (7.7%) needed the use of systemic steroids to control their symptoms. The age and sex distribution of the present cohort resembles that of the other studies on OLP patients. Reticular type was the commonest in the present study and similar results were found in other studies. Buccal mucosa was the commonest site of affliction. There were no cases with evidence of dysplasia or transformed to malignancy. Furthermore, it was not possible to comment on the treatment outcome or the malignant transformation at this stage of the study as the present group of patients is on follow up.
Chemistry of Two Leprarioid Lichens from Sri Lanka
(University of Peradeniya, 2004-11-10) Kathiragamanathar, S.; Karunaratne, V.; Kumar, V.
We reported the two species of lichens 𝘓𝘦𝘱𝘳𝘰𝘭𝘰𝘮𝘢 𝘴𝘪𝘱𝘮𝘢𝘯𝘪𝘢𝘯𝘶𝘮 and 𝘓𝘦𝘱𝘳𝘢𝘳𝘪𝘢 𝘢𝘵𝘳𝘰𝘵𝘰𝘮𝘦𝘯𝘵𝘰𝘴𝘢 from Sri Lanka in 2000. The former which was collected from Beragala, was previously reported from South Africa, Colombia and Brazil while the latter, collected from Ramboda, is a new species. The compounds, atranorin 1, β-sitosterol 2, (+)-usnic acid 3, zeorin 4 and a C₋₄₃ fatty acid ester 5 have been isolated previously from the hexane and dichloromethane extracts of 𝘓 𝘴𝘪𝘱𝘮𝘢𝘯𝘪𝘢𝘯𝘶𝘮. In the present study the methanol extract and the lichen powder of this lichen yielded compounds 1-5 in addition to glyceryl trilinolate 6, 3, 6-dimethyl-2-hydroxy-4- methoxybenzoic acid 7 and a triterpenoid 3β-acetoxyfem-9(11)-ene 8. Chromatography of the lichen powder of 𝘓 𝘢𝘵𝘳𝘰𝘵𝘰𝘮𝘦𝘯𝘵𝘰𝘴𝘢 led to the isolation of five compounds, including compounds 1-4 along with methyl-β-orcinolcarboxylate 9. All compounds were characterized by the physical data (mp, TLC and co-TLC) and spectroscopic methods (UV, ¹H NMR, ¹³C NMR, ²D NMR and MS) [The abstract also includes scientific formulas and symbols to represent key concepts and findings].
Chemical Constituents of 𝘈𝘳𝘵𝘰𝘤𝘢𝘳𝘱𝘶𝘴 𝘈𝘭𝘵𝘪𝘭𝘪𝘴
(University of Peradeniya Sri Lanka, 2004-11-10) Jayasinghe, U. L. B.; Amarasinghe, N. R.
In a continuation of our studies on search for biologically active compounds from Sri Lankan plants the present study was carried out on the fruits of 𝘈𝘳𝘵𝘰𝘤𝘢𝘳𝘱𝘶𝘴 𝘈𝘭𝘵𝘪𝘭𝘪𝘴 (Park.) Fosb .. 𝘈. 𝘢𝘭𝘵𝘪𝘭𝘪𝘴 of the family Moraceae is a tree of moderate size, commonly known as bread fruit growing in tropical countries[The abstract also includes scientific formulas and symbols to represent key concepts and findings]. The dried powdered fruits of 𝘈𝘳𝘵𝘰𝘤𝘢𝘳𝘱𝘶𝘴 𝘢𝘭𝘵𝘪𝘭𝘪𝘴 were defatted with n-hexane and extracted with ethyl acetate and methanol at room temperature. Preliminary investigation indicated the presence of antifungal active compounds against 𝘊𝘭𝘢𝘥𝘰𝘴𝘱𝘰𝘳𝘪𝘶𝘮 𝘤𝘭𝘢𝘥𝘰𝘴𝘱𝘰𝘳𝘪𝘰𝘪𝘥𝘦𝘴 in both ethyl acetate and methanol extracts in the same Rf region by TLC bioautography method. In order to isolate antifungal active compounds, both ethyl acetate and methanol extracts were combined and separated by a combination of chromatographies over column of silica gel, Sephadex LH-20, reverse phase silica gel and reverse phase HPLC to give seven compounds. Four of them were identified as (𝘌)-4-(3-methyl-E-but-1-enyl)-3,5,2', 4'- tetrahydroxystilbene (1), (𝘌)-3,5,2',4' -tetrahydroxystilbene (2), 2-(2,4-dihydroxyphenyl)- 5,7-dihydroxychroman-4-one (3) and 2-(3,5-dihydroxyphenyl) benzofuran-4, 6-diol (4). Structure elucidation of isolates was based on the detailed analysis of ¹HNMR, ¹³CNMR, MS and direct comparison of the reported data. All these compounds showed radical scavenging properties towards 2,2' -diphenyl-I-picrylhydrazyl (DPPH) radical by TLC bio-autography method. Structure elucidation of the other three compounds and determination of antioxidant activity (IC₅₀) and antifungal activity (MIC) of isolates are in progress.

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