Browsing by Author "Rathnayake, A."

Now showing 1 - 3 of 3

Community prevalence of childhood asthma and atopy
(Sri Lanka Medical Association, 2005) Perera, K.P.J.; Rathnayake, A.; Wickramasinghe, N.; Muthukumarana, S.
OBJECTIVES: To estimate prevalence of childhood asthma, allergic rhino conjunctivitis and eczema in the community using an interviewer administered questionnaire. To estimate the extent of prophylaxis usage in asthma. SETTINGS: A cross sectional descriptive study in 2003. METHOD: Sample consists of children between 6 months to 13 years (n=2005) in 4 PHM areas randomly selected from Ragama. Diagnosis was based on presence of symptoms in preceding 12 months. Information gathered using a pre-tested questionnaire. Study was ethically approved. Data analysis - Epi Info version 6. RESULTS: Mean age was 6.7 years and 52% were males. Asthma prevalence was 13%. Prevalence in infancy - 4%, 1-5 years -13%, 5-10 years - 15% and 10- 13 years - 11%. Prevalence in males -14%. In females -11% (p=0.03). Lifetime prevalence - 19%. Current wheezing rate - 1.6%. Prevalence of allergic rhinitis - 5%, allergic conjunctivitis 3% and eczema 0.8%. Of all asthmatics, 70% were mild intermittent, 23% mild persistent and 7% moderate persistent. 49% of those who required prophylaxis were already on prophylaxis. Of them, 92% on steroid inhalers. CONCLUSIONS: Prevalence of asthma and allergic rhinitis and eczema are less than when reported by parents (Parent reported prevalence were 23%, 11% and 3% respectively). The majority of asthma was mild intermittent type. Usage of prophylactic medications was nearly 50%.
Determinants of Stock Price Volatility: A Literature Review
(Department of Finance, University of Kelaniya., 2022) Hewamana, R.; Siriwardhane, D.; Rathnayake, A.
Purpose: This paper reviews the theoretical background and the empirical results of the stock price volatility determinants under three categories: macroeconomic, company-specific fundamentals, and behavioral factors. Methodology: Previous empirical and theoretical articles on volatility determinants were compared to identify the similarities and differences of the findings. The systematic literature review followed to review the articles published in English between 1930 and 2021. Design: A critical literature review was performed by comparing the findings of previous studies based on the development status of the market. We discuss determinants of stock price volatility. Determinants include behavioral (non-fundamental) factors and macro-economic factors such as GDP, Inflation, Interest Rate, Money Supply, and Exchange Rate. In addition to Earnings and Dividend Payments have been considered under company-specific fundamentals. Findings: It was found that there is no agreement between the studies on the macro-level and micro-level determinants of stock volatility. This empirical inconsistency is substantial in GDP, Inflation, Money Supply, Exchange Rate, Earnings, and Dividend Payments. The interest rate is the only determinant that shows moderate inconclusive empirical results. However, behavioral determinants appear to be significance consistency in determining the stock price volatility. Originality: This article reviews the theoretical and empirical background of stock volatility determinants since there is no single article for reviewing theoretical and empirical results. In a single paper, we provide evidence relating to the impact of macroeconomic, company-specific, and behavioral factors on stock price volatility. Research Directions – Future research is needed to examine the reason for empirical inconsistency in volatility determinants. A systematic literature review is essential.
Green synthesis and detection of antioxidative, photocatalytic and antibacterial properties of silver nanoparticles synthesized from Psidium spps. Leaves extract
(Faculty of Graduate Studies, University of Kelaniya Sri Lanka, 2022) Rathnayake, A.; Kandiah, M.
In the ever-growing field of nanotechnology, synthesis methods that use bioproducts have been proven to be a safe, non-toxic alternative to toxic chemical compounds and traditional ways of manufacture. The research presented was performed to synthesize silver nanoparticles using the green synthesis method from six species of Psidium (Guava) leaf extracts. Five of six samples produced silver nanoparticles (AgNPs) using the optimum heating condition at 90⁰C for 1 hour. The AgNPs were observed under a transmission electron microscope at the Sri Lankan Institute of Nanotechnology (SLINTEC), Homagama, to determine the morphological features, which showed circular nanoparticles of 45 nm. The band-gap energy (2.95 eV) proved that the synthesized guava AgNPs were indeed semiconductors. Water extracts tested for phytochemicals (flavonoids, quinones, carbohydrates, proteins, saponins, steroids, tannins, terpenoids and anthraquinones), showed all positive results for the apple guava and variegated guava samples. The antioxidant content of AgNPs and water extracts were determined using Total Flavonoid Content (TFC), Total Phenolic Content (TPC), Total Antioxidant Content (TAC) tests and radical scavenging methods such as DPPH and IC50. Significant difference of antioxidant activity between AgNPs and water extracts was demonstrated by ONE-WAY ANOVA analysis at P<0.05. There is a significant difference in TFC and TPC between AgNPs and water extracts although, a considerable difference between AgNPs and water extracts were not seen during TAC testing (P>0.05). The water extracts showed higher TPC, TAC, DPPH and IC50 while the AgNPs showed higher TFC. Pearson correlation demonstrated a strong positive (0.82) correlation between TAC and TPC demonstrating a simultaneous increase of both variables. Both TFC vs TAC (-0.34) and TPC vs TFC (-0.28) relationships had weak negative correlations. The degradation rate of methyl-red dye measured the photocatalytic activity of the AgNPs. The results were compared between two concentrations (100 ppm and 4000 ppm), with and without a catalyst. The degradation rate was highest with the sample of 4000 ppm with catalyst (R2= 0.74). The antibacterial activity of the water extract and AgNPs were determined using the well diffusion method for E. coli and S. aureus. Water extracts showed higher zones of inhibition than AgNPs. ONE-WAY ANOVA analysis carried out on zones of inhibition observed by water extracts and AgNPs against E. coli and S. aureus showed no significant difference. The results obtained by the tests carried out on the Psidium water extracts and AgNP samples provide biocompatible solutions to antimicrobial therapies and azo-dye degradation due to antioxidative properties that can be used to improve the quality of life.