Electronic Edition

An electronic edition of this journal is available at http://link.springer.de or at http://link.springer-ny.com

Alert service. Would you like to automatically receive via e-mail news of newly published articles listed in the journal‘s table of contents with direct links to the respective abstracts? Then take advantage of our free Alert service. To register and obtain further information, go to http://link.springer.de/alert/ or http://link.springer-ny.com/alert/

Online First publication. Online First articles are published in electronic form weeks before distribution of the printed journal. An online publication date is published in each Online First article and its print version. Authors should be aware that after electronic publication they cannot withdraw an article or change its content. Any corrections have to be made in an Erratum which will be hyperlinked to the article. Online First articles can be cited using their Digital Object Identifier (DOI), a unique and consistent identification code, included in both the print and the electronic versions.

((This is an explanation of the Online First workflow. This text will be published on standard page.))