I am much honored to announce the fifth regular issue of the year 2013. I want gratefully thank all institutions and individuals - including the consortium members, editorial board members and the authors - for all their dedication and support of the journal.

In this issue we have five accepted regular papers on various topics of computer science. In a collaborative research between Saudi Arabia and Spain, Habib M. Fardoun, Abdulfattah Mashat and Sebastián Romero López focus on cloud computing for education. An investigation into the relationship between perceived quality and virtual acoustic environments is discussed by an international research collaboration from Canada, Germany and France by Khalil ur Rehman Laghari, Tiago H. Falk, Mansoor Hyder, Michael Haun, Christian Hoene and Noel Crespi. Miloš Ljubojević from Bosnia Herzegovina as well as Vojkan Vasković and Dušan Starević from Serbia report on their analysis of the users' response to the linear internet video advertising by applying QoE methods. Alois Paulin affiliated in Austria and Slovenia contributes to e-government by a novel model for governing societies based on modern information technology. In their collaborative research between Spain and Saudi Arabia, Pedro G. Villanueva, Ricardo Tesoriero, José A. Gallud, and Abdulrahman H. Altalhi introduce a framework to develop web applications based on RFID panels.

Also in this issue are three accepted papers on models and knowledge representation contributed by three guest editors. Miguel-Angel Sicilia (University of Alcala, Spain), Nikos Manouselis (Agro-Know Technologies, Greece) and Pythagoras Karampiperis (NCSR Demokritos, Greece) detail their review and selection process as follows: "This issue includes a selection of papers that are covering topics related to applied models and knowledge representation in computational science. They have been collected through an open invitation to the presenters of two relevant events:
- The 2013 edition Workshop on Knowledge REpresentation and Applied Models in computational science (KREAM'13, http://www.ieru.org/org/kream/2013/) that took place in conjunction with the International Conference on Computational Science (ICCS'13)
- The presenters of the 2012 edition of the Recommender Systems Challenge Workshop (RecSysChallenge'12, http://2012.recsyschallenge.com) that took place in conjunction with the ACM Recommender Systems Conference (RecSys'12)
Five (5) submissions have been received and undergone a thorough peer-review process according to the JUCS standards.

The Guest Editors have selected three of them that, according to the reviewers' opinion, meet the quality standards of the journal." Josiane Michalak Hauagge Dall Agnol and Cesar Augusto Tacla from Brazil outline a method for collaborative argumentation in merging individual ontologies. Balazs Hidasi and Domonkos Tikk from Hungary discuss matrix factorization methods on implicit feedback databases. In their collaborative research Leonardo Lezcano from Spain, Brigitte Jörg from UK, Brian Lowe and Jon Corson-Rikert from USA contribute on international interoperability of research information systems.

Enjoy reading!

Cordially,

Christian Gütl, Managing Editor
Graz University of Technology, Graz, Austria
Email: cguetl@iicm.edu