About the Authors

N. D. B. Ehelepola

Roles Conceptualization, Data curation, Formal analysis, Methodology, Project administration, Visualization, Writing – original draft, Writing – review & editing

drehelepola@gmail.com

Affiliation The Teaching (General) Hospital–Peradeniya, Peradeniya, Sri Lanka

Kusalika Ariyaratne

Roles Data curation, Formal analysis, Writing – original draft, Writing – review & editing

Affiliation Lanka Hydraulic Institute, Moratuwa, Sri Lanka

D. S. Dissanayake

Roles Data curation, Validation, Writing – review & editing

Affiliation Faculty of Medicine, University of Peradeniya, Peradeniya, Sri Lanka

Competing Interests

Employers of all authors were not involved in this study in anyway and this was done during authors’ free time independent of their duties. During the period of study they received their usual salaries for their usual duties. No funding was received for this work. The cost was mainly borne by the 1st author. Second author who performed wavelet analysis and wrote that section in the manuscript is an engineer working for a commercial company. However that commercial affiliation did not play any role in our study. Also it does not alter our adherence to PLOS ONE policies on sharing data and materials.