PURSE 2001
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- ItemAn assessment of energy substitution possibilites in the Sri Lankan economy(University of Peradeniya, Peradeniya, Sri Lanka, 2001-11-16) Dissnayake, M.N.; Gunatileka, H.M.Energy is a very important input in the production process of a country. Sri Lanka imports its entire requirement of crude oil and oil products. Domestic energy resources consist of only biomass and hydropower. Higher dependency of an economy on a particular input, especially when large amount of that input are imported, renders the economy vulnerable to external price shocks. Sri Lankan energy importation statistics show that the demand for imported energy is increasing by 9% per annum and neariy 3% of the country's GDP is spent on energy imports. Therefore, external energy price shocks can have a profound impact on the Sri Lankan economy. In fact, the current economic slow down in Sri Lanka is partly due the higher energy prices There are many ways to reduce the dependency of an economy on imported energy. This study explored one such possibilities: substitution of energy with other inputs. The objectives of this study were to examine substitution possibilities between energy and non energv inputs in Sri Lanka and to identify the responsiveness of factor demand to price changes The specific aim was to estimate the elasticity of substitution for the basic factors of production in the Sri Lankan economy to check the substitutability among them. In addition, own I price and cross price elasticities of demand were estimated to examine the price responsiveness of energy inputs. The selected factors of production for the analysis were labour, capital and petroleum 1 based energy Data on GDP, quantity of labor, quantity of petroleum energy, amount of capital, 1 price of petroleum, interest rates and wage rates were collected from different secondary sources. Quarterly data for the period of 1990-1999 were used in the analysis Data limitations did not allow extension of the data set for the periods before 1990. Factor share equations for labor, capital and petroleum energy, derived from a Translog production function, were estimated. The estimation was carried out as a system of equations using Seemingly Unrelated Regression ( method. Price elasticities and elasticities of substitution were calculated using estimated share equation parameters. The results reveals that the petroleum energy is price inelastic and it behaves as a complement with other two inputs Hence, the results imply that, substitution possibilities of both labor and capital, in place of energy, do not exist given the structure of the economy. Of the two ways 10 reduce energy dependency, i.e., energy conservation and substitution, these results suggest that energy conservation is the only possible way to deai with the situation. To achieve higher efficiency from energy conservation practices, various educational, administrative and fiscal measures can be used as part of the government policy Results also show that the use of price as a mechanism to reduce energy consumption will not be an effective reform strategy due to price inelasticity of energy.
- ItemAntimicrobial Activity of Some Sri Lankan Rubiaceae and Meliaceae(University of Peradeniya, Peradeniya, Sri Lanka, 2001-11-16) Jayasinghe, U. L. B.; Jayasooriya, C. P.; Bandara, B. M. R.; Ekanayake, S. P.; Merlini, L.; Assante, GContinuing our work on biologically active compounds from Sri Lankan plants we have now screened 94 solvent extracts (n-hexane, dichloromethane and methanol) obtained from leaves, bark and stem of thirteen Rubiaceae species (Benkara malabarica, Canthium coromandelicum, Canthium dicoccum, Haldina cordifolia, Ixora calycina, Morinda tinctoria, Mussaendafrondosa, Psychotria gardneri, Psychotria nigra, Psycho tria stenophylla, Saprosma foetens, Tarenna asiatica and Wendlandia bicuspidatay and two Meliaceae species (Aglia congylos and Munronia pumilia) for antibacterial activity against Escherichia coli (Ec), Micrococcus luteus (Ml), Bacillus subtilis (Bs) and Bacillus cereus (Bc) and antifungal activity against Saccharomyces cerevisiae (Se), Ustilago maydis (Um) and Aspergillus niger (An). Screening for antimicrobial activity was carried out using the disc diffusion method. The media used for culturing bacteria, fungi and yeast like fungi were nutrient agar, Czapek agar and glucose yeast agar, respectively. The plants M.tinctoria, M.frondosa, P. gardneri and P. stenophylla showed antimicrobial activity against at least five of the seven microbes examined: M. tinetoria (leaves) - hexane extract against Ec, Bs, Be and An, and dichloromethane extract against Sc, Ec and Be; M tinetoria(bark) - dichloromethane extract against Se, Ec, Bs and An, and methanol extract against MI and Be; M frondosa (leaves) - dichloromethane extract against Sc, Ec, Bs and Be, and methanol extract against Bs; M frondosa (bark) - hexane extract against Sc, Um, Ml and Be, dichloromethane extract against Se, MI and Be, and methanol extract against Ec and Bs; P. gardneri (leaves) - dichloromethane extract against An,. and methanol extract against Sc, £C, Ml and Be; P. gardneri (bark) - hexane extract against An, dichloromethane extract against Se and Bs, and methanol extract against Ec, MI, Bs and Be; P. stenophylla (leaves) - dichloromethane extract against Ec; P. stenophylla (bark) - dichloromethane extract against Um, £C, MI, Bs, Be and An and methanol extract against MI. The following extracts were found to be inactive: A. congylos (leaves - methanol), B. malabarica (leaves - hexane), C. coromandelicum (leaves - hexane), H. eordifolia (leaves -hexane, bark - hexane and methanol), I. calycina (bark - hexane), M tinetoria (leaves-methanol, bark - hexane), M. frondosa (leaves - hexane), M puma/ia (leaves - hexane, dichloromethane and methanol), P. gardneri (leaves - hexane), P. nigra (leaves - hexane and dichloromethane), P. stenophylla (leaves - hexane and methanol, bark - hexane), S. foetens (bark - hexane), T asiatica (bark - hexane), W bicuspidata (leaves - methanol, bark - methanol).
- ItemApple tissue base biosensor for thiram(University of Peradeniya, Peradeniya, Sri Lanka, 2001-11-16) Weliwegamage, U. S. K.; Navaratne, A.Some plant tissues, such as pineapple, tea, apple and potatoe tissues, contain the enzyme; called polyphenol oxidase, which catalyses the oxidation of catechol to o-quinone in the primary enzymatic step. Thiram is a frequently used dithiocarbamate fungicide in vegetable cultivations world wide including Sri Lanka. It is also used as a seed protectant and as a soil spray. The excess amounts of thiram pollute the water resources and soil in agricultural areas. Hence the trace level determination ofthiram is highly desirable. An electrochemical biosensor was developed to detect thiram using the apple tissue polyphenol oxidase. The enzyme interacts with thiram to give an oxidative voltammetric behavior: an oxidation peak was clearly observed at +0.10V vs. SCE in phosphate buffer solution at pH 7. The electrochemical response of thiram-enzyme system depends strongly on the solution pH. The peak current responses observed at pH 1,3, 5, 7 and 9 were 0.00 µA, 3.00 µA, 6.75 µA, 11.25 µA and 8.75 µA respectively. Further the continuous scanning studies carried out at same medium suggested that the analyte is highly adsorbed on to the electrode surface during this process. The voltammetric response shows a significant dependence on medium pH. The optimum pH for the voltammetric process was found to be 7, where the best pH reported for the reactivity of polyphenol oxidase. The method was used to detect thiram in a standard solution of 1.0x 10-6 mol dm-3, which was accomplished by preconcentration of analyte on modified electrode prior to cyclic voltammetric analysis. In the preconcentration process, the solution was stirred for an accumulation period of 15 min with applying a potential of O.OOV vs. SCE as the accumulation potential.
- ItemApplication of CO2 laser for oral soft tissu surgery in children(University of Peradeniya, Peradeniya, Sri Lanka, 2001-11-16) Jayawardena, J. A.; Kato, J.; Wijeyeweera, R. L.Lasers are increasingly being used for many operative procedures in Dentistry. One of these lasers, namely C02, has been reported to be very .effective in surgery involving oral soft tissues. CO2 laser is capable of incising and excising soft tissues through a mechanism called tissue vaporization, during which a surface coagulation layer is produced, at the operating site. As a result, the operating field remains clear during the operation, and there is no need of suturing after the operative procedure. The objective of this study was to clarify the effect of C02 laser irradiation on oral soft tissue problems of children in Sri Lanka. In this report the continuous C02 laser at 10.6J.L m with low power was used in 20 subjects, aged between 2 and 15 years, having main indications for labial frenectomy, treatment of ankyloglossia and excision of mucocele. The results indicated that C02 laser has the following advantages 1. The operation time required was lesser when compared with the conventional surgical procedure. 2. The procedure of the operation was simple. Hence, there was no need of general anaesthesia. 3. There was no post-surgical infection. 4. The contraction and scarring of the wound was minimal. We conclude that the use of CO2 laser is a safe and effective method for soft tissue surgery in children.
- ItemAnalytic philosophy: A brief appraisal(University of Peradeniya, Peradeniya, Sri Lanka, 2001-11-16) Kalansuriya, A. D. P.Analytic philosophers identify the very subject of Philosophy with an analysis of words, terms, notions, expressions, statements, etc.. Wittgenstein gave a new impulse to analytic philosophy with the radiant notion, namely, "A main source of our failure to understand is that we do not command a clear view of the use of words." This is a clear recognition of human failure together with a committed estimate of the ability to engineer solutions for problems that have befallen the best brain since the Greeks. "A clear view of the use of words." But, then, what does it mean? One has to note the nature of the discourse, that of the doctrine, that of the argument, etc. (to which Wittgenstein says 'language game') in which it finds expression that is its original home, in which alone it meaning. Two conclusions follow (i) that confusions, which occupy us do not arise. (ii) which are already there, can be dispelled. The implication being a therapeutic one reminds of a prescription for doing philosophy. That is, putting the word in its linguistic context and whole statement in its native context. But, then, how does one do this? By accepting and mastering analytic techniques. The resuIt: To bring words back from their metaphysical to everyday usage (L Wittgenstein, 'Phylosophical Investigations, 1953: 48e), implying that metaphysics does not have a logic of its own whereas other discourses have a logic of their own. Implied are "chains of reasoning" or "forms of life" in all discourses other than 'philosophy'; for 'philosophy' is not a discourse an analytic activity. Based on this concept of "chains of reasoning," one sees not only the nature of the discourse--science, religion, aesthetics, etc. but also the limits pertaining to 'truth' or 'falsity' of statements that come within first-order disciplines. This brings out the very base of Analytic phylosophy understood and practiced in the English-speaking world as a second-order discipline.