PURSE 2002

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    Effect of Crowding on Frequency of Bolton Tooth Size Discreapncies Among Orthodontic patients
    (The university of Peradeniya, 2002-10-30) Nagarathne, N.
    The aim of the study was to examine the frequency of Bolton tooth size discrepancies and the effect of severity of crowding on tooth size discrepancies among orthodontic patients. A random sample of 146 orthodontic patients 74 males and 72 females who satisfied the selection criteria were selected from the records of the orthodontic patients taken up between year 1997 to 2000. Mesio distal dimensions of the teeth mesial to both maxillary and mandibular first permanent molars were measured on pre treatment study models and subjected to Bolton analysis. Both overall and anterior Bolton ratios were calculated for each case. The severity of crowding was assessed using Little's Irregularity Index. Data analysis was done to investigate the frequency of tooth size discrepancies among both crowded and non-crowded groups and the effect of severity of crowding on tooth size discrepancies. There were 68 in crowded group and 78 in non-crowded group. 26.91 % of the crowded group showed clinically significant (2SD out side of Bolton mean) anterior tooth size discrepancies which can compromise the final occlusal outcome. Mean overall ratio for non-crowded group was 90.95%±2.49% and for crowded group was 90.95%±2.94%. Mean anterior ratio for non-crowded group was 76.41%±3.09% and for crowded group was 78.10%±3.23%. Statistically significant difference was seen only in anterior retios between crowded and non-crowded groups. (P=. 002). Results of the study reveals that special emphasis should be given to the Bolton analysis of anterior ratios, during treatment planning stage of orthodontic cases with crowding in order to reduce the failure rate which can result due to tooth size discrepancies in the study population.
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    Effect of Differant Processing and Pakaging Methods on Quality and Storage Life of Dry Fish
    (The university of Peradeniya, 2002-10-30) Dilrukshie, M. G. N.; Cyril, H. W.
    Dry fish is widely consumed by the people in Sri Lanka. Sun drying is a common method to produce dry fish. High percentage of post-harvest loss can occur when processing is done under this traditional system due to reabsorption of moisture, fungal bacterial and insects attacks. If the processed dry fish is not packed properly, it can lead to storage losses and poor quality end product. The objectives of this study were to improve the quality of the dry fish by using oven dry method and adding spices and to study the effect of packaging on keeping quality. Five treatments, salted and sun dried, salted and oven dried, salted with 3% pepper and oven dried, salted with 1.5% pepper + 1.5% garlic and oven dried and salted with 1.5% pepper + 1.5% mustard and oven dried were prepared. Salted dried fish were cut into small cubes (1m3) and were packed in polypropylene packages under vacuum and ambient condition. They were stored at room temperature at 27°C. Colour, pH, rancidity and moisture content were measured in all treatments and results were statistically analyzed by SAS(2000 version). A taste panel was conducted to evaluate attributes, appearance, taste, colour, texture and juiciness on a seven point hedonic scale to select best one. The data was analyzed by Firdman non-parametric test. According to Firdman test, salted sun dried sample had the highest sensory values. pH value of all the samples were decreased during the storage time. pH values of salted sun dried sample (6.04) was lowest than that of all other treatments. TBA value (rancidity) was increased with the storage time. TBA values of salted sun dried sample and salted oven dried sample were significantly higher than that of oven dried spice added samples. Moisture content was not changed considerably with the storage time but it was higher in salted sun dried sample (26.17%) and lower in salted oven dried sample (18.67%). Colour indexes, lightness (L*), redness (a*) and yellowness (b*) of the dry fish samples were fluctuated with the storage time. pH changes, rancidity development and moisture changes were significantly lower in vacuum packed products than normal packed products. The rancidity development, pH changes can be controlled by adding spices. Moisture content of the product can be reduced by oven dried method. Vacuum packaging of dry fish improved the keeping quality.
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    Effect of differant processing and pakaging methods on quality and storage life of dry fish
    (The university of Peradeniya, 2002-10-30) Dilrukshie, M. G. N.; Cyril, H. W.
    Dry fish is widely consumed by the people in Sri Lanka. Sun drying is a common method to produce dry fish. High percentage of post-harvest loss can occur when processing is done under this traditional system due to reabsorption of moisture, fungal bacterial and insects attacks. If the processed dry fish is not packed properly, it can lead to storage losses and poor quality end product. The objectives of this study were to improve the quality of the dry fish by using oven dry method and adding spices and to study the effect of packaging on keeping quality. Five treatments, salted and sun dried, salted and oven dried, salted with 3% pepper and oven dried, salted with 1.5% pepper + 1.5% garlic and oven dried and salted with 1.5% pepper + 1.5% mustard and oven dried were prepared. Salted dried fish were cut into small cubes (1m3 ) and were packed in polypropylene packages under vacuum and ambient condition. They were stored at room temperature at 27°C. Colour, pH, rancidity and moisture content were measured in all treatments and results were statistically analyzed by SAS(2000 version). A taste panel was conducted to evaluate attributes, appearance, taste, colour, texture and juiciness on a seven point hedonic scale to select best one. The data was analyzed by Firdman non-parametric test. According to Firdman test, salted sun dried sample had the highest sensory values. pH value of all the samples were decreased during the storage time. pH values of salted sun dried sample (6.04) was lowest than that of all other treatments. TBA value (rancidity) was increased with the storage time. TBA values of salted sun dried sample and salted oven dried sample were significantly higher than that of oven dried spice added samples. Moisture content was not changed considerably with the storage time but it was higher in salted sun dried sample (26.17%) and lower in salted oven dried sample (18.67%). Colour indexes, lightness (L*), redness (a*) and yellowness (b*) of the dry fish samples were fluctuated with the storage time. pH changes, rancidity development and moisture changes were significantly lower in vacuum packed products than normal packed products. The rancidity development, pH changes can be controlled by adding spices. Moisture content of the product can be reduced by oven dried method. Vacuum packaging of dry fish improved the keeping quality
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    Effect of different haemoglobins on the glucose 6 phophate dehydrogenase deficiency screening test (brewer's test)
    (The university of Peradeniya, 2002-10-30) Sugathadasa, B. H. K. R.; Perera, P. A. J.; Dissanayake, D. M.
    Glucose 6-phosphate dehydrogenase (G6PD) deficiency is the commonest enzymopathy causing haemolytic anemia in humans. Haemoglobinopathies too contribute towards haemolytic anemia in Sri Lanka. The laboratory investigations of chronic haemolytic anaemia include, screening test and enzyme assay to exclude G6PD deficiency. Haemoglobinopathies and thalassaemic syndromes are excluded by haemoglobin electrophoresis. Even though G6PD enzyme assay is indicated for diagnosis of G6PD deficiency, due to lack of reagents all the government hospitals in Sri Lanka employ only the screening test (Brewer's test) for the diagnosis. The aim of the study is to observe the effect of different haemoglobins on screening test for G6PD deficiency. We investigated patients & carriers for haemoglobinopatheis (Hb E, Hb S, Hb D) using G6PD deficiency screening test as well as G6PD enzyme assay. The results show that Haemoglobin E present in Haemoglobin Elf} thalassemia, Haemoglobin E trait and Haemoglobin E disease, gives a false positive reaction with G6PD screening test. Forty-four out of forty nine subjects (93.9%) with haemoglobin E were positive for G6PD screening test, even though their G6PD enzyme levels were normal, Two subjects showed low enzyme levels with positive screening test. Only three out of forty nine (6.2%) were negative for G6PD screening test. Haemoglobin S (n=5) and Haemoglobin D (n=2) did not show any effect on the screening test for G6PD deficiency. Haemoglobin E is the commonest haemoglobinopathy in Sri Lanka, with high prevalence in Kurunegala, Anuradhapura and Chilaw districts. If only the screening test is utilized in the diagnosis of G6PD deficiency, the patients with Haemoglobin E are likely to be labeled as G6PD deficient, while having normal enzyme levels. Therefore G6PD enzyme assay should be used in the diagnosis of G6PD deficiency, at least in districts with high Haemoglobin E prevalence.
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    Effect of Lantana camara as a photosensitizing agent in crossbrd friesian cattle
    (The university of Peradeniya, 2002-10-30) Wijewardana, V.; Gajanayake, T. N.; Jayaweera, T. S. P.
    Lantana is commonly found along roadsides, fence-rows, and in fields in Sri Lanka and during the scarcity of natural forages grazing animals tend to consume Lantana in considerable amounts. Lantana poisoning in grazing animals has been documented elsewhere. The major clinical effect of Lantana toxicity is photosensitization. As a consequent raw photosensitised surface areas are susceptible to invasion by maggots and bacteria. This causes severe economic loss in terms of reduced milk yield in cows and poor growth and occasional mortality among calves. Experiments were carried out at Boralanda area in the up country dry zone (average temperature 27> C, average relative humidity 65%, average rainfall 1500 - 2000 mm) during month July/August 2002. Crossbred Friesian cattle (300 kg live weight in average were used for the experiments. Animals were located in a type of housing system where they are exposed to sunlight throughout the day. The experiment was designed with 3 animals per group. Animals received a ration of Panicum maximum and Gliricidia sepium and one of three levels of fresh leaves of Lantana camara (Control group: 0 gld; Treatment 1: 1 kg /d; Treatment 2:2 kg /d Treatment 3:3 Kg /d). Lantana camara was offered at the morning meal before the feeding of forages. Clean and fresh water was available ad libitum during the whole experiment. Concentrates and mineral mixture were offered to all animals at the rate of 1 kgld and 100 gld respectively. Animals were fed twice daily at 8:00 am and 2:00 pm. Test feed was fed 5 days. Blood samples were taken two days before the start of the experiment, through out the test feeding period and 2 days following the completion of the test feed. Animals were observed clinically and the blood samples obtained were analysed for haematology and serum enzymes. The Group 3, which was fed with 3 kgld of Lantana camara, started to show signs of photosensitization after 3 days following commencement of feeding. Photosensitization was most prominent on areas of the body with least protection from sunlight. Further, affected animals had pyrexia, intense pruritis and irritation. Haematology revealed neutrophilia and eosinophilia. The alanine aminotransferase (ALT) and aspartate aminotransferase (AST) levels also increased significantly. Group 1 and Group 2 did not show any signs of photosensitization and other parameters were within the normal range. This experiment shows that feeding of Lantana camara above the dose of 1% of the body weights creates photosensitization in crossbred Frisian cattle. Elevated levels of AL T and AST occurred as a result of compromised liver functions, which reduce the excretion of plant pigment metabolites from the body. Subsequently these photodynamic agents produced the effect when exposed to ultraviolet light.
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    Effect of probiotics on growth performance, carcass characteristics and occurrence of salmonellosis in broilers fed on local diets
    (The university of Peradeniya, 2002-10-30) Priyankarage, N.; Silva, S. S. P.; Gunaratne, S. P.; Palliyaguru, M. W. C. D.; Kothalawala, H.
    In the modem day intensive poultry farming, broilers are subjected to various kinds of stresses, which adversely effect the performance of birds and causes high incidences of diseases such as salmonellosis. Antibiotics have been widely used as feed additives to counteract these adverse effects and to control harmful organisms. However, continued use of sub therapeutic levels of antibiotics in animal feeding has been known to cause several public health hazards. Therefore the use of antibiotics as feed additives has been banned in several countries and the Sri Lankan authorities would soon follow the ban. Further indiscriminate use of antibiotics resulted in the emergence of resistant infective agents of certain diseases like salmonellosis. Probiotics, which are live microbial feed supplements, are claimed to be environmentally friendly additives, which competitively excludes the pathogenic organisms and beneficially alters the intestinal microbial flora in order to enhance health status, growth performance and feed conversion efficiency of poultry. Although probiotics have been widely used as an alternative for antibiotics elsewhere, their efficacy under local conditions have not been studied. In this experiment, the efficacy of a multi-strain commercial probiotic mixture on commercial broilers was assessed under local conditions. A control diet (C) was formulated and three treatment diets were prepared by adding probiotics to the control diet at 0.01 % (TI), 0.02% (T2) and 0.03% (T3) levels. All four diets were replicated three times and tested on 240, day old broiler chicks (20 birds per replicate) for the full period of 42 days. Performances were analysed at weekly intervals and carcass characteristics were assessed at the end of the experiment. Since the chicks that were used in the experiment were found to be infected with Salmonella pu//orum, antibodies for Salmonella pullorum was tested using rapid agglutination test with stained Salmonella pullorum antigen on day 42. Results were analyzed using one-way ANOV A and means were separated by Tukey's pairwise comparison. Although the numerical values for performance and carcass characteristics were better, for the treatment groups, than in the control group, these differences were not statistically significant. The effect of probiotic on salmonella on the other hand was statistically significant (P>0.05). Highest number of sero-positives (43%) was detected in control group and no sero-positives were found in T3 group. There was a negative correlation between level of probiotic in the diet and the incidence of salmonella in the flock (20% inTI and 13% T2), which support the notion of competitive exclusion of probiotics. Further, economical analysis revealed that there is a cost advantage of adding probiotics to the diet at prevailing market prices.
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    Engineering analysis and fatigue evaluation of ancient riveted wrought iron railway bridges
    (The University of Peradeniya, 2002-10-30) Siriwardane, S. A. S. C.; Adasooriya, A. M. N. D.; Herath, K. R. B.; Dissanayake, P. B. R.; Mauroof, A. L. M.; Ranweera, M. P.
    Evaluation of load carrying capacity and remaining service life of railway bridges in Sri Lanka has become of primary importance since most of the major bridges in the country are more than 50 to 100 years old. The task of dealing with these old bridges has become complex as many codes of practice do not provide necessary guidelines for identification of the condition and for evaluating the remaining service life. The analysis of a railway bridge was carried out as a case study. The method adopted in evaluating the remaining service life of the bridge was the Miner-Palmgren cumulative damage rule. The bridge considered was a semi-through bridge having eight double system Warren girders supported by cylindrical piers. Several member sets were used in the analysis of the structure considering various cross-sectional properties. The most highly stressed member, i.e. the critical member of each of the member sets was taken into consideration for life evaluation. The aim of this exercise was to find out the remaining service life of each set of members. Out of the various forms of structural failures applicable to bridges the bridge considered was most likely to fail due to the effect of fatigue. The service stresses in the bridge were evaluated using a validated 3D finite element model and the stress cycle distribution of the service conditions were found from the analyses and as well as from the field tests. An impact factor based on the measured strains in dynamic field tests was used for this evaluation. The Miner's summation rule was used in the prediction of the fatigue life of the bridge. Elements of a structure may be subjected to many forms of stress cycles varying both in range and in magnitude. Each element of the structure should be designed considering the number of cycles of different magnitude to which the element is likely to be subjected during the expected life of the structure. The number of cycles of each magnitude must be estimated by the designer in the light of available data, considering the probable frequency of occurrence of each type of loading. Due to fatigue under current loadings, speeds, and frequencies of operation, the lowest remaining life found for a member under the investigation was found to be 20 years. Thus, it may be concluded that the Bridge deck can be used for another 20 years provided that the speed, frequency, and the weight of the trains are not increased from the present value. If proper maintenance work is carried out and critical members are replaced by new members having longer life, the bridge may be able to provide service for a further period.
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    Establishment cell cultures of tea (Camellia sinensis L.) to study programmed cell death (PHD) in plants.
    (The University of Peradeniya, 2002-10-30) Thilalakarathne, C. L.; Gunawarena, A. H. L. A. N.; Gunasekare, M. T. K.
    Tea (Camellia sinensis L.) is highly heterozygous and predominantly cross-pollinated woody perennial crop. Therefore, the development of improved plant materials through conventional breeding is a laborious and time-consuming task. Alternatively, cell cultures hold great promise in the production of improved cultivars of tea. As there are no studies done in the past to perfect the conditions necessary for establishing cell cultures isolated from plant tissues of tea, the present study aimed at perfecting such conditions. There is clear evidence that Programmed Cell Death (PCD) occurs during plant development and environment response. However, the signals that trigger PCD in plants are unknown. In plants, selective cell death is necessary for growth and survival. Therefore, cell cultures are used to study PCD in vitro. A system was established for isolation of single cells from surface sterilized leaf tissues by digesting them in an enzyme mixture containing 1% (w/v) Macerozyme in cell and protoplast washing medium and mannitol (CPW 1.6 M) for 3 hours. Cells were purified by centrifugation followed by washing in CPW l.6 M solution. Culture density (5x104) was adjusted by counting purified cell suspension on a haemocytometer. Purified isolated cells were then, cultured in Murashige and Skoog basal medium containing 3 % (w/v) sucrose and 1.6 % (w/v) mannitol devoid of growth regulators. Cell viability was determined by staining cells with 0.25 % (w/v) Evan's blue. Characteristics related to PCD were observed using a light microscope. For optimizing yield and viability of isolated cells, factors such as concentrations of enzymes and mannitol, stage or the age of the leaf, type of explant and digestion time were examined. Of the factors tested, optimum yield and viability of cells were obtained when second leaf from the shoot apex was digested with 1% (w/v) Macerozyme in CPW 1.6 M for 3 hours. Under these conditions, it was possible to achieve 1.6 x 106 - 2.0 x 106 cells per gram fresh weight of leaf tissue with viability ranging from 75 - 78 %. Under similar conditions however, in vitro leaf tissues resulted inferior quality cells as well as more protoplasts than cells. Cell division started at 24 hours after culture. Percentage of dividing cells reached its peak 144 hours (6 days) after culture and declined afterwards. One of the characteristics of PCD, condensation of cytoplasm was observed in freshly isolated cells and dividing cells. Dead cells were stained in blue color whereas viable cells were remained unstained. For further studies of PCD characteristics, transmission electron microscopic observations are needed
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    Local changes in contraction related substences in Bovine Oviducts exposed to ovarian steroids and peptides; investigation by in vitro microdiaysis system
    (The University of Peradeniya, 2002-10-30) Wijayagunawardane, M. P. B.; Weerathunga, H. A. S. K.
    The microenvironment in the oviduct is controled by the endocrine, paracrine and autocrine interactions mediated by ovarian and pituitary hormones as well as by the local oviductal products. Thus, in this study, microdialysis system (MDS) was utilized to investigate the effect of luteinizing hormone (LH), oxytocin (OT) and ovarian steroids (progesterone; P4 and estradiol-l Zp; E2) added to the incubation medium on the local secretion of prostaglandins (pG), endothelin-l (ET-I) and angiotensin II (Ang II). A 7 em long microdialysis capillary membrane was implanted in to the lumen of the oviducts collected from post ovulatory phase of the estrous cycle, incubated in TCM 199 in simple organ culture chambers, and the system was gently perfused with Ringer's solution. Addition of LH, ET -1 and LH+ET -1 to the incubation medium induced PGE2 release and the highest stimulatory effect on PGE2 secretion was observed with the combination ofLH+ET- l+E2+P4. The administration of LH, ET-l, P4+E2, LH+ET-l, LH+ET-l+ E2+P4 show a stimulatory effect on PGF2a release. LH, LH+ET-l, LH+ET-l+ E2+P4 stimulate ET-l and Ang II releases. ET-l in the incubation medium stimulate it's own release. When OT was added to the incubation medium it hinders the effect of all these stimulations. The overall results of this study indicated that LH with the E2 and low P4 and/or ET-I bearing the highest stimulatory effect on the production of contraction related substances such as PGE2, PGF2a, ET -1 and Ang II. The administration of OT resulted in an inhibition of the LH stimulated effect on the oviduct. Moreover, the locally produced ET-l acted as an up regulator of it's own secretion. This results provide further evidences for our previously suggested concept on the regulation of oviductal contraction that the preovulatory LH surge, together with a locally recirculated high level of E2 from the Graafian follicle and basal P4 level from regressing corpus Iuteum (CL) induces the maximum stimulation in the oviductal production of PG and ET-l, resulting in the active oviductal contraction for a rapid transport of gametes. OT released from the newly formed CL may block these mechanisms, thus inhibiting the contraction to secure a slow transport of the embryo to the uterus.
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    Student teacher interaction and learing outcome
    (The University of Peradeniya, 2002-10-30) Wickramarachchi, W. A. R.; Sugathapala, R. D.
    In student learning, a variety of theoretical perspectives focus on the contrast between the organizations of knowledge as discrete, serial elements to be remembered and the integration and transformation of knowledge in to a personally constructed meaning full entity. Marton (1975) first made this distinction when he described approaches to learning in terms of either deep or surface processing of information. This conceptualization has led to much further theoretical development (Biggs. 1987: Entwiste, et al. 1991). Biggs (1989, 1982) has developed an interactive system model of teaching and learning map how students' general conception of learning, interact with characteristics in the learning environment to produce learning outcomes. This system has three components: Presage, Process and Product. Presage factors include not only the students characteristics but also the learning context involving teacher and teaching methods. The specific learning strategies that they consequently adopt for that learning task is the process. The product of learning outcome is largely influenced by the strategy adopted and the presage factors. As a presage factors teacher and teaching methods mainly influenced to the learning outcome. Present study is based on above theoretical perspective. In this study 54 lessons conducted by student teachers who are following the Post Graduate Diploma in Education course were observed by the researches to examine the effects of teaching strategies on students' learning process and product, direct observations and semi structured interviews were conducted for four students from each class. Data were analyzed qualitatively. From the analyzes of data, some important facts were revealed. On the strength of revealed facts following conclusions were made. 1. Whcn teachers focus strongly on active participation of students and creating a supporting environment, students focused on student-centered aspects of the class. 2. In contrast, when traditional expository teaching methods were used students mainly focused on transmission and reproduction.
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    The effect of fish type, marination and smoke source on the quality of smoked fish product
    (The University of Peradeniya, 2002-10-30) Ananthi, K.; Cyril, H. W.; Ganepola, M.
    Smoking is an ancient technique that is commonly used in contribution with brining and curing. In industrialized countries, smoking of fish is done for enhancement of flavor and texture. it adds considerable value to the fish. Smoking provide partial protection against microbiological, enzymatic and chemical deterioration. Fish is main seafood act as protein rich source. Since smoking of fish act as value adding process and preservative measure, smoked fish product was developed to fulfill the requirements of producer and consumers. Five fish types namely seer, mallet, lo-musso, travelly and shark were filleted and, smoked after dipping into the standard brine solution (7ppm). Then samples were subjected to an untrained taste panel to select the best types for smoking. Sensory evaluation was conducted based on 5-point Hedonic scale and result was analyzed using Friedman test. Subsequently, selected fishes seer and mallet were dipped into different recipies of brines, soy source with white wine brine, honey cured brine, onion cheese spread, and mayonnaise and, smoked. Through sensory analysis honey cured brine was selected as best marination for seer fish and soy source with white wine brine was selected as best marination for mallet fish. Thereafter seer fish which was marinated with honey cured brine and mallet fish which was marinated with soy source with white wine brine were smoked using different smoke sources such as Cinnamon saw dust and Clove leaves. Through sensory analysis best product was selected. Finally Seer fish marinated with Honey cured brine and smoked by Cinnamon wood dust and saw dust combination (2: 1) was selected as best product. The overall acceptability was considered mainly to select best treatment. Then the selected best product was packed in vacuum and normal packing and stored at the temperature of 4 ± 2°C and quality of the product was checked weekly by measuring pH, color, water holding capacity, rancidity(TBA value), water activity and total plate count until 4 weeks of time. Even though water activity was higher in the smoked seer fish, microbial level was satisfactory (less than 105 CFU/g of smoked fish) for both packaging types up to 4th weeks of storage at 4 ± 2°C. The pH, TBA value and water holding capacity were increased rapidly with storage period on smoked seer fish, which packed under normal conditions than that packed under vacuum. This indicates vacuum packing was improved storage life of smoked fish product