Resonance journal of science education Editorial Board Chief Editor S Mahadevan Associate Editors J H Arakeri, Bangalore D N Rao, Bangalore G Nagendrappa, Bangalore Renuka Ravindran, Bangalore Vasant Natarajan, Bangalore K L Sebastian, Bangalore Biman Nath, Bangalore Priti Shankar, Bangalore D P Patil, Bangalore Council of Editors K B Athreya, USA Bikram Phookun, New Delhi Anand K Bachhawat, Chandigarh C R Pranesachar, Bangalore V Balakrishnan, Chennai T P Radhakrishnan, Hyderabad B V Rajaram Bhat, Bangalore V Rajaraman, Bangalore Dipankar Bhattacharya, Bangalore S Ramasubramanian, Bangalore M K Chandrashekaran, Bangalore K Sankara Rao, Bangalore S R Gadre, Pune D M Salunke, New Delhi S R Ghorpade, Mumbai L S Sashidhara, Hyderabad A P Gore, Pune Shailesh A Shirali, Chickmagalur Amitabh Joshi, Bangalore Mewa Singh, Mysore · G Marimuthu, Madurai J Srinivasan, Bangalore N Mukunda, Bangalore Akhilesh K Tyagi, New Delhi Utpal Nath, Bangalore Raghavan Varadarajan, Bangalore Editor of Publications N Mukunda, Indian Institute of Science, Bangalore Assistant Editors M Raj Lakshmi, Sujatha Mohankumar Production G Chandramohan Editorial Staff G Madhavan, R Pushpa, M Srimathi, Circulation and Accounts Shanthi Bhasker, B V Bhoja Raja, Peter Jayaraj, B Krishna, Ranjini Mohan, C Vedamurthy, C Visweswaraiah Annual Subscription Rates Institutions: Rs.400/-; Individuals: Rs.350/- minimum for two years; Price per single copy: Rs.40/- All correspondence regarding subscription should be addressed to The Circulation Department of the Academy. Email:[email protected]; Online orders for India are also accepted at Scholars without Borders (www.scholarswithoutborders.in) Email:[email protected] Editorial Office: Indian Academy of Sciences, C V Raman Avenue, PB No. 8005, Bangalore 560 080, India. Tel: +91 (80) 2361 2943 / 2361 2546, Fax: +91 (80) 2361 6094, Email: [email protected] Website: http://www.ias.ac.in/resonance; http://www.iisc.ernet.in/academy/resonance International subscriptions are processed by Springer (www.springer.com) For details contact: The Americas (North, South, Central and the Caribbean): journals-ny@ springer. com Outside the Americas: [email protected] © 2007 by the Indian Academy of Sciences. All rights reserved..