Submitted on: 24 July 2007.
Revised on: 20 October 2007.
Accepted on: 01 December 2007.
___________________Epidemiology and Psychiatric Sciences
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Submitted on: 16 May 2009.
Revised on: 18 August 2009.
Accepted on: 15 October 2009.
___________________Epidemiology and Psychiatric Sciences
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Submitted on: 07 December 2002.
Revised on: 03 February 2003.
Accepted on: 17 March 2003.
___________________Epidemiology and Psychiatric Sciences