Article history: Received 9 December 2013 Received in revised form 17 April 2014 Accepted 2 July 2014 Available online 10 July 2014

Article history: Received 19 September 2014 Received in revised form 19 November 2014 Accepted 22 December 2014 Available online 2 January 2015

Article history: Received 2 September 2013 Received in revised form 7 July 2014 Accepted 12 July 2014 Available online 17 July 2014 Communicated by Jared Tanner

Article history: Received 19 September 2014 Received in revised form 19 November 2014 Accepted 22 December 2014 Available online 2 January 20

Article history: Received 19 October 2013 Received in revised form 5 August 2014 Accepted 16 August 2014 Available online 2 September 2014

Article history: Received 2 July 2013 Received in revised form 24 February 2014 Accepted 11 April 2014 Available online 24 April 2014

Article history: Received 8 April 2013 Received in revised form 2 June 2014 Accepted 18 June 2014 Available online 8 July 2014 Communicated by H. Prodinger

Article history: Received 15 January 2013 Received in revised form 24 May 2014 Accepted 22 September 2014 Available online 2 October 2014

Article history: Received 15 July 2013 Received in revised form 18 April 2014 Accepted 23 May 2014 Available online 2 June 2014

Article history: Received 10 April 2013 Received in revised form 14 September 2014 Accepted 24 September 2014 Available online 2 October 2014