PURSE 2000

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A device made to measure and control bite force of human subjects in recording EMG activity of muscles of mastication
(University of Peradeniya, 2000-12-16) Pallegama, L. N.; Pallegama, R. W.; Sitheeque, M. A. M.; Weerasinghe, V.S.; Ranasinghe, A.W.; Somaratne, A.P.N.
Electromyographic activity (EMG) of muscles of mastication is recorded for various research and clinical activities related to masticatory complex. Integrated EMG activity· as well as the degree of biting force generated depend on the number of motor units involved in contraction of the muscles. Therefore, in recording EMG activity of muscles of mastication the bite force has to be controlled. Further, subjects must have a visual feedback to control and maintain the bite force during the recording period. The objective of the present study was to design and prepare a reusable and reliable electronic device that can be used to control and measure the bite force of human subjects in recording EMG activity of muscles of mastication. This prepared transducer consists of a stainless steel bite piece that can withstand the bite force of humans within the elastic limit of the material. A strain gauge (KFG-I 0-120-C I L5 M3 S) was attached to the outer surface of the stainless steel bite piece to measure the strain that is directly proportional to the bite force. The strain gauge was connected to a bridge circuit and the resultant signal was passed through an amplifier and then fed to an analogue multimeter. The multimeter reading provided the visual feedback required by the subject. The EMG activity of masseter and anterior temporalis was recorded in ten dentulous young adults while maintaining the bite force with this transducer. The visual feedback given through the multimeter was sufficient for subjects to maintain the bite force during the recording period The bite piece of the transducer was placed in between upper and lower incisors on each subject and they were asked to maintain four different loads using the visual feedback. The EMG activity was recorded under four different loads in all subjects. The recorded EMG activity was proportional (y = 0.9) to the bite force and it can be concluded that with the aid of this device the bite force of human subjects can be satisfactorily controlled in recording EMG activity of muscles of mastication.
A study of the musical poetical forms and their contribution to the emotional expressions in the sokari drama
(University of Peradeniya, 2000-12-16) Seneheweera, L
Kolam, Nadagam. and the Sokari have been established as the folk drama in Sri Lanka. Kolam is a kind of a dramatic pcrfonnance. which survives today chiefly in coastal townships in South in Sri Lanka. particularly in Ambalangoda and Bentara. Nadagamas have been popular mostly in villages and townships along the western coast. from Chilaw in the north right down to places like Tangalle in the South. The Sokari is a folk ritual drama with much dramatic entertainment. confined to the Uda Rata and the Vanniya. Presently it is performed in the villages around Kandy. Traditions of Sokari performed at Uda Dumbara. Matale. Konakallagala. Vehigala arc well known, This ritual play in many of its tradition is performed to get the blessings of the goddess Paththini, However. in some tradition Kataragama with that part is emphasized: the story enumerates how Guruhamy and Sokari after their marriage came to Sri Lanka from South India to visit the famous devale of Kataragarna in order to get the blessings of that god to beget a child. The story is dramatically presented by players who resort to mime. dance and stylized movements as a backup for the normal prose and verse dialogue. In addition. there is much variation in poetical forms. although it may seem monotonous for a non-initiate. The play is lyrical and consists of a large number of verses. These could be divided into two categories of metrical and non-metrical composition, both of which could again be subdivided into measured and unmeasured forms: a large number of meters including Samudurugos. yagi. so on. Furthermore. it uses a large number of poetical forms such as sivupada. gi. sahali. as well as musical forms of rhythm. melody. and tempo. One could sum up that Sokan play is based on the genuine folk. poetical. and musical traditions of the upcountry tradition of Sri Lanka. The aim of the present research is to highlight this basic musical tradition,
An anlysis of legislation for protection of the environment and its impact on health
(University of Peradeniya, 2000-12-16) Gooneratne, I.; Gooneratne, N.
Health services in Sri Lanka are provided mainly through the Ministry of Health, local authorities, and private sector, but at present it is the government that is responsible to render public health! community health services. It is a known fact that the environment has an impact on health. For many years environmental health has been a legal responsibility of national and provincial health authorities, but the control of environmental factors affecting health has long been shared by other ministries, agencies and agents. The purpose of this study was to analyze the legislation for protection of the environment and its impact on health. Among the laws that have been enacted to protect the environment, quarantine and prevention of diseases ordinance, housing and town improvement ordinance, town and country planning ordinance, food act, cosmetic and drugs act, control of pesticides act, national environmental act, medical ordinance, urban development authority act, the nuisance act. central environmental authority law, and constitution of Sri Lanka and its amendments were shown to have an impact on health
An experimental cryptosporidium infection in mice and goat kids
(University of Peradeniya, 2000-12-16) Noordeen, F.; Horadagoda, N. U.; Faizal, A. C. M.
Cryptosporidiuni parvum, a zoonotic protozoan parasite of mammals. occurs throughout the world. Following infection, it multiplies within the microvilli of the enterocytes and produces pathological changes associated with clinical signs in susceptible hosts. Studies on experimental Cryptosporidium infections in various species reveal that the infectivity varies with the host species and the strain of the parasite. This paper describes the infectivity. pattern of oocyst shedding. and the morphological changes in the intestine following an experimental Cryptosporidium infection in goat kids. Crvptosporidiuni oocysts, isolated from adult asymptomatic goats. were identified as C parvuni by Polymerase Chain Reaction. Two. -l-day-old goat kids were infected orally' with C pan'IIJII oocysts (l05 oocysts in 10 ml phosphate buffered salinelkid) and an age-matched goat kid given an equal volume of phosphate buffered saline (PBS) by the same route served as a control. In addition, eight I-week-old mice were infected orally (103 oocysts/mouse) for comparative purposes. Crvptosporidium oocysts were detected in the feces of one infected kid on 3 days post inoculation (dpi) whereas in the other 6 dpi, The faecal oocyst counts gradually increased and the peak counts in both kids were 2 x 10° g'' (on 12 dpi) and 3.2 x 106 s" (on l-l dpi). The increase in faecal oocyst output coincided with diarrhoea in an infected kid from 10 to 17 dpi. Although. the oocyst excretion declined gradually after the peak. both infected kids excreted oocysts until euthanized on 20 and 22 dpi, Light and scanning electron microscopic investigations of the ileum revealed the developmental stages of the parasite within the brush border of the enterocytes, infiltration of neutrophils and mononuclear cells into the lamina propria, and atrophy. stunting and fusion of villi, All experimental mice excreted oocysts from 3 dpi, and -l infected mice continued to excrete oocysts until -l2 dpi. Thus, the experimental infection in goat kids resembled the natural disease in terms of oocyst excretion, clinical signs. and intestinal pathology. The ability of oocysts excreted by asymptomatic goats to infect goat kids and mice is likely to have a major impact on the epidemiology of cryptosporidiosis in livestock and man
Assessment of contamination of milk at different stages of collection
(University of Peradeniya, 2000-12-16) Hathurusinghe, M.H.; Horadagoda, A.; Fernando, P.S.; Weihena, S.
Good quality milk in relation to composition and hygiene is a basic requirement to process the 'ready to drink' milk which is presently in great demand. Inevitably this market trend has stimulated milk-procuring agencies to examine milk for both composition and quality of milk at the various stages in the collection chain. A very large proportion of milk in Sri Lanka is produced by small holder dairy farmers where clean milk drawn directly from the udder is likely to be contaminated before it reaches a processing plant. Polluted water. unclean receptacles. long transit time with increased environmental temperatures. are some of the potential causes for increased bacterial counts in milk which reflect contamination. The purpose of this study was to identify the amount of contamination of milk at the different stages of collection and the influence of preservatives in reducing such contantination. The study was conducted among .to dairy farmers in three villages around Kandy. The fanners were visited three times during a period of six months. In the first visit. a sample of milk was collected to determine the degree of contarrtination. At the second visit a sample was collected for the California mastitis test (CMT) and the third visit was made to create an awareness of the importance of clean milk production. Ten per cent of sample drawn from the udder was positive for Methylene-Blue dye Reduction test (MBRT) after one hour. In contrast. 15% of milk samples collected from the bucket and 50% of the samples collected at the Milk Collecting Centers were found to be positive for MBRT after one hour. and by the end of the third hour all the collecting center samples were found to be positive. It was observed that polluted water and general unhygienic conditions were the main contributors to contamination of milk. Among the samples collected from the three villages, the management practices in one village was very poor. In this village even the samples collected directly from the udder were found to be heavily contaminated and 77% of them gave a positive reaction to the CMT. The addition of hydrogen peroxide was found to reduce the bacterial counts indicating that it is a useful preservative. The third visit helped to educate fanners on cleaner milk production resulting in a better price for their milk.
Assessment of contamination of milk at diffrent stages of collection
(University of Peradeniya, 2000-12-16) Hathurusinghe, M. H.; Horadagoda, A.
Good quality milk in relation to composition and hygiene is a basic requirement to process the 'ready to drink' milk which is presently in great demand. Inevitably this market trend has stimulated milk-procuring agencies to examine milk for both composition and quality of milk at the various stages in the collection chain. A very large proportion of milk in Sri Lanka is produced by small holder dairy farmers where clean milk drawn directly from the udder is likely to be contaminated before it reaches a processing plant. Polluted water. unclean receptacles. long transit time with increased environmental temperatures. are some of the potential causes for increased bacterial counts in milk which reflect contamination. The purpose of this study was to identify the amount of contamination of milk at the different stages of collection and the influence of preservatives in reducing such contantination. The study was conducted among .to dairy farmers in three villages around Kandy. The fanners were visited three times during a period of six months. In the first visit. a sample of milk was collected to determine the degree of contarrtination. At the second visit a sample was collected for the California mastitis test (CMT) and the third visit was made to create an awareness of the importance of clean milk production. Ten per cent of sample drawn from the udder was positive for Methylene-Blue dye Reduction test (MBRT) after one hour. In contrast. 15% of milk samples collected from the bucket and 50% of the samples collected at the Milk Collecting Centers were found to be positive for MBRT after one hour. and by the end of the third hour all the collecting center samples were found to be positive. It was observed that polluted water and general unhygienic conditions were the main contributors to contamination of milk. Among the samples collected from the three villages, the management practices in one village was very poor. In this village even the samples collected directly from the udder were found to be heavily contaminated and 77% of them gave a positive reaction to the CMT. The addition of hydrogen peroxide was found to reduce the bacterial counts indicating that it is a useful preservative. The third visit helped to educate fanners on cleaner milk production resulting in a better price for their milk.
Bone formation and remodeling pattern in the mandible
(University of Peradeniya, Peradeniya, 2000-12-16) Arambaawtta, A. K. S.; Peiris, H. R. D.; Nanayakkara, D.
The development of the mandible occurs mainly by intramembranous ossification. However, its subsequent growth is brought about by the secondary cartilages that appear in the heads of the condyles. The present study was carried out to identify the bone formation and remodeling pattern in the mandible, and to establish the rate of bone formation at different sites in the mandible. Five male and five female Sprague Dawley rats receiving a normal diet were mated. From the day of mating, a bone marker, Calcein (flurescein methylene iminodiacetic acid- 30mglkg body weight), was injected intraperitoneally to the female rats at weekly intervals. This was continued on the new born rats up to seven weeks and the rats were sacrificed. Ground sections were prepared from the condyle and the base of the mandible. The observations under fluorescent microscopy revealed that the pattern of bone formation differed in the condyle and the base of the mandible. Clear fluorescent lines arranged in an organized manner were seen in the base. This arrangement was absent in the condyle and the fluorescent material was deposited in a random manner. In the growth cartilage of the condyle the proliferating cartilage cells are not arranged in columns as in the growth cartilage of a long bone. Therefore, the growth at the condylar head is multidirectional and fluorescent lines are not seen. The distance between fluorescent lines were measured using a calibrated ocular grid at the buccal alveolar bone, lingual alveolar bone, and the basal bone of the mandible. The mean values of bone formation obtained for these sites were 10.00 ± 9.16 11m, 42.8S± 00 11mand 2186± 10.39 11mrespectively. 195
Changes in physicochemical characteristics in saanan goat milk throughout a lactation
(University of Peradeniya, 2000-12-16) Dangolla, A; Silva, I. D.; Gunawardena, A.
Values on cellular and physicochemical characteristics of milk are helpful to detect the degree of sub clinical and/or clinical mastitis in goats. Since these values are likely to change throughout a lactation, for diagnosis of mastitis, a correlation with the stage of lactation is necessary The objective of the present investigation was to examine the changes in cellular and physicochemical characteristics of goat milk throughout a lactation. Composite milk samples from 10 goats from a farm in Matara, were collected into sterile glass containers, sealed air tight, labelled, and transported in ice to the veterinary diagnostic laboratory of the University of Peradeniya. At the onset of sampling, the goats were either in their 2nd or 3rd lactation and were approximately 2 weeks after kidding. Seven successive samplings were done in approximately one-month intervals by the same person. The somatic cell count (See), California Mastitis Test (CMT) reading, electrical conductivity (EC) and chloride ion concentration (Cl %) were measured within 48-72 hours after sampling. The climatic data for the area were also recorded. Sampling commenced in July 1999 and continued till January 2000. Only thirty-eight samples were processed and analyzed, as all the 10 goats were not sampled on every occasion due to unavoidable circumstances. The mean SCC (xl03/ml) values on the 7 consecutive sampling dates were 380, 1055, 3087, 2495, 4460, 2931, and 1600; the EC (milliSiemens/cm) values were 4.80,5.34,432,5.34,4.55, 10.86, and 7.01; and CI % values were 0.08,0.08,0.08,0.06,0.06, and 0.11 %, respectively The chloride ion concentration was not analyzed on the first sample collected. The average temperature, relative humidity, and rainfall during the period were 28.3° F, 78%, and 1200 mm respectively The goats were fed with jak leaves, Bracharia brizantha, and Prima feed mixture, containing 9-12%,8.5%, and 15% protein, respectively on dry matter basis). A progressive elevation in the sce during the first 4 months, followed by a decline during the last two months was observed. However, 16 out of 38 samples analyzed had CMT scores> 1 indicating a substantial frequency of subclinical mastitis. Consequently, the increase followed by the decline in sec remained even after disregarding the high SCC values corresponding to > J CMT scores. There was no obvious difference in the values between the 2nd and 3rd lactation, at any of the sampling dates. A notable change was not evident in EC or CI% throughout a lactation. There is evidence in these data to suggest that there is an increase in sec throughout a lactation in Saanan goats and therefore, the sce values must be interpreted in relation to the stage of lactation. However, further studies on a larger number of samples are necessary to establish this 202 phenomenon on SCC (if any), in EC, or CI % throughout a given lactation. It appears that CMT readings on goat milk do not correspond well with SCC values when performed 48 hours after milk collection. This finding becomes important when dispatching and transporting goat milk samples to a distant laboratory, in order to detect subclinical mastitis in the field.
Design and construction of an electronic water level indicator
(University of Peradeniya, 2000-12-16) Bandara, H. M. P.; Dissanayake, M. A. K. L.
The increasing availability of low cost semiconductor devices has led to the rapid proliferation of economical electronic devices applicable to all aspects of life. However. in Sri Lanka. though there is a large market for electronic devices of all types. design and development of new electronic devices remain a weak sector. For those who depend on water from an overhead tank. it is important to know the amount of water available in the tank. This is particularly important when the main water supply is not reliable. The possibility to know the amount of water in an overhead tank without having to frequently access it is therefore important and useful. Commercially available water level indicators are expensive and needs frequent care and maintenance. The aim of this project is to design and construct an electronic water level indicator using readily available low cost electronic devices and materials. In designing the instrument special emphasis was laid on minimising cost without compromising accuracy. At the same time a special effort was made to make the instrument simple and thereby reducing the need for maintenance.
Development of "EdRex" a computer pakage for the automation of examination procedures in the Faculty of Agriculture
(University of Peradeniya, 2000-12-16) Wickramasuriya, H. V. A.; Basnayake, M.; Angammana, A.
The efficient functioning of the Examination Unit is essential for the smooth administration of a university faculty. Therefore. the objective was to develop a software package for the Examination Unit. It was an in-house development through End User Computing at negligible financial cost. The package was developed as an application of Access' with Visual Basic'. Product development took two years during which time a Beta version and two other versions were rigorously tested. At present the product enables instantaneous registration of a full batch. of compulsory courses, and easy registration of optional courses. the generation of class lists. class attendance sheets. admission cards, examination attendance sheets. mark sheets. results sheets. and transcripts. Response time for each process is less than 2 seconds. enabling a very significant increase in the efficiency of the Unit. Some security features were provided. User support and training "ere provided. This package is currently being used in the Faculty and the response received has been extremely positive.
Diagnostic testing of power transformer insulation by response measurements in frequency domain
(University of Peradeniya, 2000-12-16) Mularachchi, K.; Fernando, M.
This paper presents results of frequency domain response measurements on field-aged power transformer insulation comprising oil and cellulose material (paper. pressboard. etc.). Different types of oil-paper insulated power transformers were selected from the hydropower stations in Sri Lanka. The loss tangent of the transformer insulation was measured over a broad frequency range. It is shown that the variation of loss tangent over frequency provides an easy classification of new and aged transformers.
Effect of dexamethasone on the metabolism of testosterone in human gingival fibroblasts
(University of Peradeniya, 2000-12-16) Tilakaratne, A.; Soory, M.
Dexamethasone has been known to have synergistic interactions with growth factors to induce proliferation of human diploid periodontal ligament and gingival fibroblasts. It can also stimulate the formation of new cementum and alveolar bone. The anabolic effects of androgens especially 5a-dihydrotestosterone (DHT) are well established. The aim of this investigation was to study the effects of dexamethasone (Dex) on the metabolism of testosterone in human gingival fibroblasts (HGF). Confluent monolayer cultures of HGF of 5th_9'h passage derived from chronically inflamed gingival tissues were established in Eagle's Minimum Essential medium. Duplicate incubations were performed with 14C-testosterone (l4C-T) as substrate and serial concentrations of Dex ranging from 0.5-50 ug/ml for 24 hours. At the end of the incubation period. the steroid metabolites were ana lysed and quantified using a radioisotope scanner. Most of the lower concentrations of Dex showed a stimulatory effect on DHT synthesis from 14C-T. with a maximum increase of 44% at 1.0 ug/ml, decreasing to 14% at 10 ug/ml and reaching control values at higher concentrations. The increases in DHT in response to the lower concentrations of Dex (ranging from 0.5-8.0 ug/ml) were statistically significant (n=6: p<0.05: ANOYA). Synthesis of the other major metabolite. -l-andrcstenedione from 14C-T showed 20- 36% increases in response to the range of 0.5-5.0 ug/ml of De x (n=6: p<0.05: ANOYA). Dexamethasone at lower concentrations could induce the metabolism of testosterone in cultured human gingival fibroblasts resulting in the formation of anabolic metabolites. This could enhance connective tissue and bone matrix synthesis and play an important role in tissue regeneration in inflammatory periodontal lesions.
Effect of environmental physiological and managemental parameters at insemination on conception rate of exotic (European) indigenous cows
(University of Peradeniya, 2000-12-16) Perera, E. R. K.; Udayanga, H. N. R.; Jayaweera, N.; Perera, A. N. F.
One hundred and one Exotic (European) * Indigenous crossbred cows presented for artificial insemination (AI) at Pannala Veterinary Range from April to July. 2000 were used to examine the effect. of environmental temperature (ET). various physiological parameters of the cows. and management factors at the time of insemination. on conception rate (CR) of Exotic (European) * Indigenous crossbred cows in Sri Lanka. Data on breed. age. parity, date of last calving, average daily milk yield and interval from detection of heat to insemination (IDI) of each cow were recorded based on the information provided by the owner. Environmental temperature (ET), vaginal temperature (VT). rectal temperature (RT). pulse rate (PR), respiration rate (RR), length and width of vulva, and body condition score (BCS) of individual cows at the time of insemination were measured. Heat signs (HS) of each cow at the time of insemination were assessed by adopting a scoring system, which assigned a score for each heat symptom examined. based on its intensity of expression, Two experienced technicians performed all 101 inseminations. Time of insemination and inseminator number were recorded for each insemination. Per rectal pregnancy diagnosis was performed at 75 days after insemination. Data were subjected to correlation and regression analysis. and analysis of variance procedures. Mean ET at the time of insemination was 31.2 ± 1.5 "C. resembling the typical daytime temperature conditions prevailing during these months in the intermediate zone of Sri Lanka. Mean age, parity, days postpartum (OPP) and BCS of cows were 5.39 ±2.74 yr, 2.52 ±1.55, 213±115 d and 2.7-1-± 0.65, respectively. These values suggest that the cows included in the study were a representative sample of the normal population of breedable cows. Mean PRo RR. VT and RT of 101 cows at the time of insemination were 68.-1-±2.4 beats/min. 24.6 ±1.5 breaths/min. 39.-1-5±0.38 °C and 38.5 ±0.4 °C, respectively. The values of physiological parameters were within the nonnal range for cattle. Relationships between ET at the time of insemination. and individual PRo RR, RT, and VT were positive. indicating increase in body temperature at higher ET despite induced thermoregulatory responses. Mean VT was 0.9 ± 0.1 ° C higher than mean RT in cows. and VT and RT were positively correlated (r = 0.58. p<0.05). Conception rate (65.-1-±1.2 %) was not significantly different between the two technicians. CR was highest in cows with BCS of 2 to 3, parity of 2 to 3. between 61 and 150 DPP. and when ID! was <13 hr. Inseminations performed after 19 hr lapse from detection of heat were not successful. CR declined (p < 0.05) by 8%,3.9"10. 5.2% and 4.9% with every 1°C, O.I°C. D.l°C and 1 hr increase in ET, RT. VT. at the time of insemination. and delay in time from detection of heat to insemination. respectively, CR was lowest when ET. RT. VT, and IDI at insemination were above 31.7 °C. 38.6 "C. 39.6 "C. and 19 hr. Highest CR resulted from inseminations performed whenET. RT. VT. and IDI at insemination were below 30.9 "C. 38.2 °C, 39.3 "C. and 13 hr. respectively. These trends are in the same direction. but the values are different to those reported for Holstein cows. The results suggest that CR in Exotic (European) * Indigenous cross bred cows in the sample was affected by ET. RT. yr. BCS. parity. DPP and IDI. Highest CR was resulted from inseminating cows having BCS of 2·3. parity of 3. between 61 to 150 DPP. within 13 hours of detection of heat. and when ET. RT. VI' were below 30.9 "C, 38.2 "C, and 39.3 "C. respectively.
Evaluation of Salmonella test method of Sri Lanka Standard Institute
(University of Peradeniya, 2000-12-16) Chandrasekara, R. A. N.; Jayasinghe, S.; Silva, I.
This study was conducted to evaluate the microbiological test method of Sri Lanka Standards Institution to detect Salmonella in foods. The SLS method was compared with the method published by Food and Agriculture Organization for detection of Salmonella by applying it to several food items. Black pepper. cinnamon, cardamom, cloves, and milk powder were artificially contaminated with Salmonella serotype H culture and uninoculated eggs were used for the study. A control test was carried out without adding the inoculum. Method of preparation of the food samples for isolation of Salmonella and the pre-enrichment media used. are specific for each food to be tested in the FAO method. However. SLS method employs the same preparatory procedure and the pre-enrichment media for almost all foods. Both methods gave positive reactions for artificially inoculated black pepper. cardamom. and milk powder. In the tests carried out for cloves and cinnamon by SLS method no positive reactions were observed whereas FAD method was able to identity the serotype H in these two spices. The anti-microbial substances in cloves and cinnamon appear to inhibit the growth of Salmonella by SLS method. In the fresh egg sample that was tested by the SLS method colonies were observed only in XLD agar. but not in Brilliant Green agar. These discrepancies observed for the test results for Salmonella leave room to suspect the applicability of the SLS method to foods.
Folate concentration in some common food article
(University of Peradeniya, 2000-12-16) Abeysekera, A.; Perera, P. A. J.; Ekanayake, N.; Weligama, K. N. H.
In this study, folate concentrations were analysed in food articles that are likely to be the major folate contributors. prepared by different m~thods. Folate levels were assessed using a microbiological technique. In the food articles that were studied, the highest folate concentration was seen in green leafy vegetables, especially Katurumurunga. The folate was destroyed on heating. However. the loss is minimized if lime is added. Eating green leaves fresh as a sambol minimized the losses incurred during cooking. Green gram contained high amounts of folate and germinating the seeds increased the folate concentration markedly. A day's requirement can be met by consuming just 14 g of bean sprouts a day.
Germination and seedling ecology of santalum album 1
(University of Peradeniya, 2000-12-16) Etampawala, E. R. L. B.; Tennakoon, K. U.; Gunatilake, C. V. S.
Santalum album (Sandalwood) is an economically important obligate woody root hemiparasitic tree naturalized in the wet and intermediate climatic zones of Sri Lanka. In recent years, there has been a rising interest in planting Sandalwood in Sri Lanka due to high domestic and international demand for the a and ~ Santalol oil obtained from the heartwood. Santalol is used for the preparation of expensive perfumes, cosmetics, and medicines. This study examines the germination and seedling ecology of S. album. Twenty seven randomly selected trees in three populations growing in the intermediate zone of Sri Lanka were sampled (3 randomly selected plants/plot/ population) to study the fruit and seed variations. The seed germination study included seven treatments and two replicates (36 seeds/replicate). The best substratum for the pre-parasitic Sandalwood was identified by growing seedlings in three potting mixtures containing sand, top soil and farm yard manure in the ratio of 2: I :1, 3: 1:0, and 1:): I respectively. The experiment included three treatments, three blocks, two replicates, and 20 seedlings/replicate. To evaluate the best pot-host species, one-month-old Sandalwood seedlings were grown in polythene bags, with five potential host species separately and without the host species as a control. The experiment comprised five treatments and a control, three blocks, two replicates, and 10seedlings/replicate. Fruit length, width, and seed length of Santalum varied significantly (p80%) germination rate. Seedlings grown in equal parts of sand, soil, and farm yard manure showed a significantly higher (p
Grid connected wind turbines-Sri Lanka experience
(University of Peradeniya, 2000-12-16) Ekanayake, J. B.
All over the world wind energy sources are becoming widely used as environmentallv friendly. small scale energy sources. In Sri Lanka. first grid connected' wind farm is now installed in Hanbantota as a pilot project. In this paper a simple model. which can be used to represent a grid-connected induction generator especially as a fixed speed and a variable speed wind turbine. is presented. Modifications that are required in the model for the analysis of variable speed wind turbine are performed. The characteristics of the fixed speed and the variable speed operation of the induction generator are obtained using the mathematical model developed. The wind statistics obtained from a site 2 km away from the pilot wind farm in Sri Lanka is analyzed. The output yield so far from this pilot wind farm is compared with the expected output. Advantages of variable speed wind turbines oyer fixed speed wind turbines for the site studied is also discussed. Finally. problems associated with grid connection of fixed speed and variable speed wind turbines are highlighted.
Insecticide resistance and the vectorial capacity of culex quinquefasciatus, the vector of filariasis
(University of Peradeniya, 2000-12-16) Karunaratne, S. H. P. P.; Hemingway, J.
Filariasis. caused by the nematode parasite Wuchereria bancrofti is endemic in Sri Lanka. The mosquito Culex quinquefasciatus is the vector of filariasis in Sri Lanka and other tropical countries. Control of this mosquito is mainly by organophosphorus insecticides. Resistance mechanism of Culex mosquitoes to organophosphorous insecticides is the elevation (increased quantities) of mosquito carboxylesterases and occurs in more than 80% of resistant Culex worldwide. Biochemical characterisation of these carboxylesterases. purified from C. quinquefasciatus from Colombo. Sri Lanka. revealed that they bind and inactivate organophosphorous insecticides very fast. Antiserum was raised against these esterases and respective genes were isolated. It was found that gene amplification was responsible for the increased production and the resistant insects have upto 80 copies of the gene. Electron- microscopic studies. using mosquito tissues and the antiserum. revealed that the enzymes in resistant insects are expressed at very high levels in the mosquito gut and sub-cuticular layer. As the parasites must pass through some of these tissues to complete their development. parasite survival and hence vectorial capacity can be affected by the insecticide resistance status of the insect. However, insecticide resistance is assumed to increase the likelihood of disease transmission by increasing the population size and allowing the mosquitoes to he longer in the presence of insecticides. This hypothesis was tested for the first time. Blood fed female C quinquefasciatus were collected from seven filariasis endemic areas in Sri Lanka. Mosquitoes were individually analysed for parasite loads by quantitative PCR and insecticide resistance by biochemical assay with para-nitrophenyl acetate (pNP A). Almost 80% of the mosquitoes were infected with W bancrofti. However. there was a strong negative correlation between esterase activity levels with pNP A and parasite RNA levels in all seven localities. Membrane feeding of the insecticide resistant and susceptible mosquito colonies with If'. bancrofti infected blood produced infective parasite larvae after twelve days in 76% of the susceptible. and none of the resistant females. Results suggest that elevated esterase activity affects the development of W bancrofti larvae which may be arrested in the gut cells of insecticide resistant. but not susceptible mosquitoes. Filarial worm infection of mosquitoes cause significant damage to the mosquito host. and high microfilaria infections result in insect mortality. The predominance of the elevated esterase-based resistance mechanism in field populations of r. quinquefasciatus may therefore be influenced by the dual roles of insecticide detoxication and reduction of microfilarial burdens.
Interactions among bees, wasps and some agricultural crop adjacent to the secondary forest at Gannoruwa
(University of Peradeniya, 2000-12-16) Karunaratne, W. A. I. P.; Gunatilleke, C. V. S.; Gunatilake, I. A. U. N.
Bees and wasps are economicaly imporatant insects as pollinators and predators. Decline of these insects is of global concern because of its impact on agricultural productivity, biological control of pests, and genetic diversity. This decline has been attributed to reduction in their natural habitats and the heavy use of insecticides. In this study the diversity of bees, their nesting sites, and activities on 37 agricultural crop species cultivated in the research fields at Gannoruwa, were examined in order to identify the specific pollinators of the crop species. Weed species and plant species found in the adjacent secondary forests were surveyed to acess its role in maintaing the populations of beneficial insects. Pollen found in the scopa (pollen carrying hairs) of bees were examined to recognize their true foraging plants. Xylocopa colonies were found nesting in wooden logs close to the cultivated lands while Ceratina sp. nested in rose stems. Colonies of social bees were not in the vicinity. Sweep netting off the vegetation caught 21 species of bees belonging to 11 (':') genera and four families of which Apis cerana. A ..florea and Trigona iridipennis were the most frequent visitors. Of the agricultural crop species surveyed Ipomoea batatas, So/anum melongena, Cucumis sativus, Persea americana and Luffa sp. were mostly foraged by bees for collecting pollen and/or nectarHedyotis and Tagetes were among the non-agricultural species frequently foraged by the bees.A number of polinators appear to be generalists visiting both agricultural and non-agricultural plant species suggesting the importance of the latter in maintaining the populations of pollinators especially during the lean periods resulting from the harvesting of annual crops at the end of their growing season.
Investigating the possibilities
(University of Peradeniya, 2000-12-16) Padmasiri, S. I.
Prawn-shell derivatives extracted in the laboratory in two different methods were tested for their turbidity removal efficiency and pH dependency and the results were compared with those of alum and commercially available chitosan. One method gave a product which behaved similar to commercial chitosan in turbidity removal efficiency. It was discovered that the diluted supernatant also showed very high turbidity removal capabilities.

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