Showing papers by "University of Peradeniya published in 1997"
TL;DR: In this paper, the frequency-dependent photocurrent response of dye-sensitized TiO2 cells to modulated illumination was analyzed and analytical expressions were derived that describe generation, collection, and recombination of electrons in a thin layer nanocrystalline solar cell under conditions of steady illumination and with a superimposed small amplitude modulation.
Abstract: The frequency-dependent photocurrent response of dye-sensitized TiO2 cells to modulated illumination is analyzed. Analytical expressions are derived that describe generation, collection, and recombination of electrons in a thin layer nanocrystalline solar cell under conditions of steady illumination and with a superimposed small amplitude modulation. The analysis considers illumination from the contact side and from the counter electrode side, and characteristic differences in the intensity-modulated photocurrent response are predicted for the two cases. The attenuation of the ac photocurrent by the RC time constant of the cell is also considered. The theoretical analysis shows that intensity modulated photocurrent spectroscopy (IMPS) can provide new insight into the dynamics of electron transport and collection in the dye-sensitized solar cell. Experimental IMPS data measured for high-efficiency dye-sensitized cells are fitted to the theoretical model using Bode plots in order to derive values of the lif...
576 citations
TL;DR: The differential response of the two hybrids to stress was greatest during the silking period, as indicated by the greater reduction in harvest index and kernel number in the old than in the new hybrid due to stress.
Abstract: Grain yield improvement of maize (Zea mays L.) hybrids in Ontario has been associated with increased stress tolerance of newer hybrids. This study was conducted to assess the effect of low soil N, weed interference, and soil water deficit on dry matter accumulation and grain yield of an older and a more recent hybrid. Studies were carried out at the Elora Research Station in 1992, 1993, and 1994 on a London loam (Aquic Hapludalf) that had been tile drained. The experiment was arranged in a split-split-split-plot design with four replications. Treatments consisted of two soil-N levels (70 and 225 kg ha -1 ), weed-free all season and weedy from the 3- to 4-leaf stage of maize, irrigation and no irrigation, and the hybrids 'pioneer 3902' (new) and 'Pride 5', (old). Maize phenology, dry matter accumulation, grain yield, stomatal conductance, leaf chlorophyll fluorescence, and leaf chlorophyll content were measured. Irrigation generally did not influence the measured parameters. Silking date and stomatal conductance during the grain-filling period were affected less by low soil N and weed interference in Pioneer 3902 than in Pride 5. Aboveground dry matter at silking and maturity was reduced about 20% by single stresses of low soil N and weed interference and about 55% by the combination of both stresses. Hybrid x stress treatment interactions for dry matter were not significant. The reduction in grain yield due to weed interference was 21% greater in Pride 5 than in pioneer 3902. The hybrid x N interaction for grain yield was not significant, because a smaller reduction in harvest index due to N stress in the new than in the old hybrid was offset by a larger reduction in dry matter accumulation during the grain-filling period. The differential response of the two hybrids to stress was greatest during the silking period, as indicated by the greater reduction in harvest index and kernel number in the old than in the new hybrid due to stress.
156 citations
TL;DR: In this article, the authors synthesize glasses in the 3TeO 2 x Li 2 O(1− x )V 2 O 5 system for 0≤ x ≤ 1.5.
87 citations
TL;DR: The surveyed community had a high knowledge of malaria, although side effects of antimalarial drugs were often confused with symptoms of the disease, and the community sought prompt diagnosis and treatment at 'western-type' facilities.
Abstract: A study of the cost of malaria at the household level, community perceptions, preventive measures and illness behaviour linked to the disease was undertaken in 5 villages in the dry zone of Sri Lanka. The surveyed community had a high knowledge of malaria, although side effects of antimalarial drugs were often confused with symptoms of the disease. The community sought prompt diagnosis and treatment at 'western-type' facilities, with 84% making use of government facilities as their first choice and 16% preferring private facilities. The preventive measures used were burning coils (54% of families) and special leaves (69% of families), and 93% of the families had their houses sprayed with insecticides. Average direct expenditure on a single malaria episode was $3 US, with some families spending more than 10% of the annual household net income per episode. The highest expenditure was on special diets for the sick person, to neutralize the perceived heating effect of the disease and its treatment.
63 citations
TL;DR: In this paper, a correlation between rainfall and malaria in the dry zone of Sri Lanka was found. But the correlation between malaria and rainfall in Sri Lanka is not as strong as it is in the wet zone.
Abstract: (1997). Correlation between rainfall and malaria in the dry zone of Sri Lanka. Annals of Tropical Medicine & Parasitology: Vol. 91, No. 8, pp. 945-949.
46 citations
TL;DR: Assessments based on densities of above-ground biomass, ground cover and frequencies of haustoria on host roots indicated that woody N2fixers (legumes and Allocasuarina) were principal hosts of Santalum, and specific hydraulic conductivities of roots of Santosalum were consistently lower than those of Acacia, a finding consistent with more conservative water use by the parasite than the host.
42 citations
TL;DR: Hustoria of Santalum act as a major site of synthesis and export of proline and might therefore play an important role in osmotic adjustment of the parasite and its related acquisition of water from hosts.
42 citations
TL;DR: Evaluated the potential for four species of nitrogen-fixing legumes to establish on exposed soil within successionally arrested grasslands of Panicum maximum and Cymbopogon nardus in the central hills of Sri Lanka to support the site-specific establishment of legume species for purposes of reforestation and watershed protection.
Abstract: Most of the world's forest has been cleared, cultivated, and then often abandoned. In many instances these areas have changed to successionally arrested grasslands, shrublands, or fernlands maintained by frequent fires and high herbivore populations. Many studies have shown that various herbaceous, nitrogen-fixing legumes can protect soil surfaces, retain soil moisture, improve soil fertility, and retard ground fires. Our objective was to ascertain if some of these species can potentially inhibit herbivory and satisfactorily establish in these arrested grassland areas to serve as sites for reforestation. We evaluated the potential for four species of nitrogen-fixing legumes (Calapogonium mucunoides, Centrosema pubescens, Desmodium ovalifolium, and Pueraria phaseoloides) to establish on exposed soil within successionally arrested grasslands of Panicum maximum and Cymbopogon nardus in the central hills of Sri Lanka. Four different sites within rectangular grassland areas were cleared of graminoids and sown with seed of each legume. Half of each clearing was protected from browsing rabbits and porcupines, and half was not protected. After 6 months, certain plots were destructively sampled to determine dry biomass gain for each species and treatment. Analyses of variance were performed to test for differences among sites, treatments, and species. All three factors revealed differences, indicating that species must be matched to site. On sites with high amounts of herbivory, D. ovalifolium had the greatest dry biomass gain after 6 months of growth, possibly because of its relatively low nitrogen and moisture content. Where herbivory was absent, P. phaseoloides and C. muconoides had the greatest dry biomass gain. Dry biomass gain of all four legume ground covers was low on sites with lowest pH and nutrient concentrations. Under conditions of low relative fertility and low pH, establishment of the tested legumes failed. Though soil moisture availability was not measured, we speculate that these low fertility sites were also prone to drought. Findings support the site-specific establishment of legume species for purposes of reforestation and watershed protection in central Sri Lanka. This work is applicable to other regions particularly dominated by successionally arrested grasslands with similar circumstances in other parts of south and southeast Asia.
42 citations
TL;DR: A 13-mo survey of immature anopheline mosquitoes breeding in surface water habitats was done at Mahameegaswewa village within the HuruluwewA watershed in north central Sri Lanka as part of a multidisciplinary study on malaria epidemiology.
Abstract: A 13-mo survey of immature anopheline mosquitoes breeding in surface water habitats was done at Mahameegaswewa village within the Huruluwewa watershed in north central Sri Lanka as part of a multidisciplinary study on malaria epidemiology. The watershed is representative of the ancient small tank-based irrigation network that still forms an important component of the rice production system in the low elevation dry zone. In total, 3,818 immatures representing 12 species were obtained from 2,940 samples taken from 5 larval habitats within the village ecosystem. Anopheles varuna Iyengar and An. culicifacies Giles were the most abundant species collected. Peak abundance in both species occurred in August-October. Anopheles barbirostris Van der Wulp and An. peditaeniatus Leicester also were abundant, but neither these nor the other anophelines attained comparable abundance to An. varuna and An. culicifacies. A clear progression in breeding habitat use from stream bed to tank bed and drainage area pools was seen in An. culicifacies during the premonsoon period. Environmental management measures to reduce or modify these habitats could potentially decrease malaria. transmission.
36 citations
TL;DR: A questionnaire investigation was used to examine anthelmintic usage and practical worm control for sheep on 50 farms selected randomly in Nyandarua District of Central Kenya, finding that sheep were drenched three or four times per year on most of the farms.
19 citations
TL;DR: In this article, a field investigation conducted between September 1994 and April 1995 in the Ritigala area indicates the factors influencing indigenous peoples' silent and formally unacknowledged engagement in forest management, including socially accepted rights to the forest, traditional links that forest fringe communities have maintained with the forest; indigenous knowledge; intra-household factors such as labour availability, needs, gender, and sources of income, as well as extra household factors like distance to the forests; demand for forest products and access to markets.
TL;DR: In this article, the authors used a cost-benefit approach to estimate the returns to the national economy from the main export processing zones in Sri Lanka, and found that the zones are dominated by textile and clothing firms, and returns in other sectors are considerably lower.
Abstract: Like many countries, Sri Lanka has used Export Processing Zones as a means of promoting manufactured exports. This article uses a cost-benefit approach to estimate the returns to the national economy from the main zones. Overall, the zones are found to be economically efficient with an economic rate of return of 23 per cent. The zones are dominated by textile and clothing firms, however, and returns in other sectors are considerably lower. Unlike zones elsewhere, profits to local investors are a significant part of national benefits. © 1997 John Wiley & Sons, Ltd.
TL;DR: Hyperhomocysteinaemia is associated with a three fold increase in coronary risk and it is found that patients with coronary ischaemia had significantly higher mean concentrations of homocysteine and its metabolite cysteine.
TL;DR: This analysis helps to situate the origin and development of malaria control within a colonial context and points to the need to decolonize malariology and malaria control policies and programs.
Abstract: The malaria control policies and programs that evolved in Sri Lanka from 1990 onward can be seen in the light of divergent discourses in relation to this “tropical disease” on the part of the ruling elites and scientific community, nationalist leaders, leftist activists and the peasantry in general. The “public health” concerns in malaria control were mediated and to some extent undermined by the divergent interests represented by the ruling elites on the one hand and the peasantry on the other. This analysis helps to situate the origin and development of malaria control within a colonial context. It points to the need to decolonize malariology and malaria control policies and programs.
TL;DR: It is concluded that chronic tea dust exposure causes increased prevalence of respiratory symptoms and a significant degree of small airways obstruction in workers exposed to tea dust for at least five years during the sifting process of tea manufacture.
Abstract: A cross-sectional study was conducted in order to determine the prevalence of respiratory symptoms and the effect on ventilatory capacity in workers exposed to tea dust for at least five years during the sifting process of tea manufacture compared to a control group of field workers who were not exposed to tea dust previously. Fifty-three subjects each in the study and control groups were matched for age, sex, ethnic group and height. Prevalence of chronic respiratory symptoms was obtained by questionnaire Spirometric measurements included forced vital capacity (FVC), forced expiratory volume in the first second (FEV, J and forced mid-expiratory flow rate (FEF^^*). The study group had a chest radiograph. The odds ratio for any chronic respiratory symptom was 11.6 (95% confidence interval [Cl] = 3.7-39.4) in the study group. Mean values for the spirometric tests were lower in the study group; the differences in FEV10 and FEF25_75% were significant. Tuberculosis was not found in the study group, while one subject (2.4%) had radiological evidence of bronchiectasis. It may therefore be concluded that chronic tea dust exposure causes increased prevalence of respiratory symptoms and a significant degree of small airways obstruction.
TL;DR: Ovarian follicles in the goat were investigated qualitatively and quantitatively with the light microscope, indicating that follicular morphology and activity are similar in goats and sheep.
TL;DR: Ajmalicine, formosanine, isomitraphylline and mitraphyllines have been isolated from the bark of Uncaria elliptica and differences in alkaloid content within the species have been observed.
TL;DR: In this paper, the authors explored how women and indigenous groups could potentially contribute to the process of environmental management and found that for women's and indigenous minority groups environmental management is an integral part of their resource use and therefore integrating locally evolved strategies is a way to stabilize, restore and sustain the survival systems.
Abstract: The work reported here explores how women and indigenous groups could potentially contribute to the process of environmental management. Women, indigenous communities and the poor are minorities due to their powerlessness. The result is that their opinions are not sought and minorities are not treated as contributors to modern development interventions. The objective of this paper is to examine how local knowledge and strategies contribute to the management of the resources of local environments. It is seen that women are marginalized in two ways. On the one hand, due to their gender, women are socialized as homemakers and family labour in farming and the management of other resources. On the other hand, women lack resources. Indigenous groups are marginalized due to the fact that their environmental management methods are not technical and cannot be institutionalized. The information extracted from two field studies conducted in Sri Lanka reveals that for women's and indigenous minority groups environmental management is an integral part of their resource use and therefore integrating locally evolved strategies is a way to stabilize, restore and sustain the survival systems. © 1997 by John Wiley & Sons, Ltd. and ERP Environment. Sustainable Development, Vol. 5, 11–20 (1997)
Journal Article•
TL;DR: Results of soil analysis confirmed continued contamination of soil in and around the home gardens and the work areas with human and dog faeces and with the knowledge of exact locations of soil pollution it was possible to advice the management on remedial measures.
Abstract: Objective To determine the degree of soil pollution in an area of high prevalence and the risk of exposure to geohelminth infection Design A cross-sectional study Setting A division of a large tea plantation in Kandy Subjects All persons resident in one division of the tea plantation, above the age of 1 year Measurements Prevalence of geohelminth infection measured by microscopic examination of faeces of the study group Soil samples from 38 specific locations, obtained on 3 different occasions, about 6 months apart, analysed for helminth ova The average temperature, rainfall and the number of rainy days during the sampling period Results Of the 99 subjects of the study group, 777% were positive for at least one geohelminth infection The prevalence rates for ascariasis, trichuriasis and hookworm infection were 54%, 28%, and 22% respectively At the first sampling, 105% of the soil samples were positive for helminth ova with 78% and 26% samples showing Ascaris and Necator ova respectively At the second sampling of the same locations nearly 40% of the samples were positive for helminth ova with 216%, 78% and 105% of the samples positive for Ascaris, Trichuris and Toxocara ova respectively At the third sampling, 262% of the samples were positive with 21%, 26% and 26% of the samples positive for Ascaris, Trichuris and Toxocara ova respectively Necator ova were found only once in 26% of the samples of the first sampling The larger number of samples positive for helminth ova were in the second and the third samplings which coincided with high rainfall in the pre-sampling period Conclusions The prevalence of geohelminthiases among the study group was high Results of soil analysis confirmed continued contamination of soil in and around the home gardens and the work areas with human and dog faeces With the knowledge of exact locations of soil pollution it was possible to advice the management on remedial measures
Journal Article•
TL;DR: Although these two instances of sparganosis were innocuous, infection is potentially dangerous as larvae are long lived and could invade vital organs.
Abstract: OBJECTIVE To report and create awareness of sparganosis, a parasitic zoonosis caused by a larval stage of Spirometra sp. SETTING Two patients with non-tender subcutaneous lumps. DIAGNOSIS CRITERIA: Morphology of solid cestode larva in excision biopsies. CONCLUSIONS Although these two instances were innocuous, infection is potentially dangerous as larvae are long lived and could invade vital organs. The most likely source of infection in Sri Lanka is ingestion of the infected first intermediate host, Cyclops, in water.
TL;DR: In this article, the authors focus on the complex nature of designing and effectively implementing policies, assuring fair access to university educational opportunities in heterogeneous societies, and analyze the different policies implemented in Sri Lanka for the last three decades todistribute the limited university level training resources in theengineering and medical faculties equally among the citizens.
Abstract: This paper focuses on the complex nature of designing andeffectively implementing policies, assuring fair access to universityeducational opportunities in heterogeneous societies. First, the universityadmission problem is modeled as a load balancing, scheduling and resourceallocation problem in a heterogeneous distributed system with policies toallocate student loads in university resources. Then the paper analyses thedifferent policies implemented in Sri Lanka for the last three decades todistribute the limited university level training resources in theengineering and medical faculties equally among the citizens. It is observed that in Sri Lanka, the schools in thirteen out of twentytwo districts did not produce a single engineering or medicine student until1974. Two districts enjoyed several times their fair share. Other districtshad less than their fair share in access to free higher education resources.It is also observed that no standardisation methods have been used in bothadding and comparing the marks received in multiple-language examinationsfor different subjects. The policy changes helped the talented low-income students who live indisadvantaged areas to set access, to begin, complete and get ahead on theirown. Furthermore, it generated a new wave of regional economic development.The same policies badly affected the happy few who enjoyed more than theirfair share of the university resources. Dube claimed the policy wasdiscriminatory and contributed to the on-going civil war (1995) .
Journal Article•
TL;DR: Suicide as a medical emergency imposes pressure on the limited resources and facilities available in intensive care units, and concrete preventive measures are mandatory to prevent loss of life and health care resources.
Abstract: OBJECTIVE: To evaluate intensive care utilisation following attempted suicide through self-poisoning. DESIGN: Retrospective analysis of clinical records. SETTING: Intensive Care Unit, Teaching Hospital, Peradeniya. PATIENTS: All patients admitted over the period 1991-1995. RESULTS: 292 patients were admitted after a suicide attempt by ingestion of a poisonous substance or drug in overdose. 52% were mechanically ventilated. The mean stay was 6 days. Daily intensive care cost averaged Rs. 8000 for a ventilated patient. Fifty three patients died. The 292 patients constituted 10.2% of the total admissions to the unit. CONCLUSIONS: Suicide as a medical emergency imposes pressure on the limited resources and facilities available in intensive care units. Concrete preventive measures are mandatory to prevent loss of life and health care resources. Language: en
TL;DR: A post-impasse framework poses Marx's theory of exploitation against the experiences of women garment workers in Free Trade Zones in Sri Lanka to illustrate how industrial development through free market channels is necessarily gendered.
Abstract: The UN Decade for Women has made it impossible for development specialists to ignore the experiences of women. Among development planners and male-centered theorists, however, women are either adde...
TL;DR: The development of a rapid nonradioactive hybridization assay using an oligonucleotide probe based on the cloned repetitive sequence of Setaria digitata is reported.
01 Jan 1997
TL;DR: The soil water characteristics have been investigated by using tensiometers, stable isotope profiles, subsurface temperature, at three different study sites to represent either wet or dry zone in Sri Lanka between the periods of 1992 and 1994 as discussed by the authors.
Abstract: The soil water characteristics have been investigated by using tensiometers, stable isotope profiles, subsurface temperature, at three different study sites to represent either wet or dry zone in Sri Lanka between the periods of 1992 and 1994.
Journal Article•
TL;DR: Pathological changes such as acanthosis, basal cell hyperplasia, intra epithelial neoplastic neoplasia, chronic Oesophagitis koilocytosis and papillomatosis occur in the oral hypopharyngeal and other areas of the oesophageal squamous mucosa, in association with squamous carcinoma of theOesophagus.
Abstract: Background Squamous carcinoma of the oesophagus, is a common tumour in Sri Lanka. A thickened and pale appearance of the oral, hypopharyngeal and oesophageal mucosa, has been observed during endoscopy. The aim of this study was to document the histological changes of the mucosa thus affected in 93 patients with squamous carcinoma of the oesophagus. Method 93 patients with oesophageal carcinoma had mucosal biopsies done from the left cheek, hypopharynx and 2.5 cm. and 5 cm above the tumour, during endoscopy for biopsy of the tumour. Paraffin sections of the biopsy stained with Haematoxylin and Eosin were examined. 25 specimens of oesophageal tissue, and tissue from the mucosa and hypopharyngeal mucosa obtained at coroners' autopsies from a comparable group served as controls (15 males, 10 females). Results The tumours were squamous carcinoma of varying grades of differentiation. The mucosal biopsies showed, acanthosis, basal cell hyperplasia, intra epithelial neoplasia (IEN) grades I-III, chronic oesophagitis, koilocytosis and papillomatosis. The mucosa of the control group only showed koilocytosis and papillomatosis in two cases. Conclusion Pathological changes such as acanthosis, basal cell hyperplasia, intra epithelial neoplasia, chronic oesophagitis koilocytosis and papillomatosis occur in the oral hypopharyngeal and other areas of the oesophageal squamous mucosa, in association with squamous carcinoma of the oesophagus.
TL;DR: In this article, novel liquid crystal (LC) cells were fabricated using polyaniline covalently attached onto ordinary glass surfaces, which fulfils three functions, namely, the substrate, the conducting medium and the template for the alignment of LC molecules.
Abstract: Novel liquid crystal (LC) cells were fabricated using polyaniline covalently attached onto ordinary glass surfaces. The latter fulfils three functions, namely, the substrate, the conducting medium and the template for the alignment of LC molecules. Both nematic and ferroelectric LC cells fabricated show perfect alignments and require comparatively low voltage for the switching of molecular orientations from one to another.
TL;DR: The prevalence of dysmenorrhoea and the resulting disability and absenteeism in school girls were studied in this paper, where the subjects comprised 345 girls from two girls' schools and 187 girls from 2 co-educational schools in Kandy.
Abstract: The prevalence of dysmenorrhoea and the resulting disability and absenteeism were studied in school girls. The subjects comprised 345 girls from 2 girls' schools and 187 girls from 2 co-educational schools in Kandy. General information and a detailed menstrual history with special emphasis on dysmenorrhoea, disability and absenteeism were obtained by means of a questionnaire. An educational programme on the significance of menstruation and simple ways of coping with dysmenorrhoea was conducted to subjects of one girls' school and one co-educational school. These were considered as the study groups while the other 2 schools were considered as the control groups. A repeat questionnaire was given to both groups 6 months later, to obtain details about the last menstrual periods. Analysis of data showed the following: A significantly higher percentage of subjects from girls' schools belonged to higher social classes (p The study indicates that social class or coeducation do not significantly affect the degree of dysmenorrhoea and the resulting disability in school girls, but may affect school attendance which could be improved by educational programmes.