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                 Senior Member of the ACM UMAP 2025 (International Conference on User Modeling, Adaptation and Personalization) International Program Committee.  |  
            
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                 Member of the ACM UMAP 2024 (International Conference on User Modeling, Adaptation and Personalization) International Program Committee.  |  
            
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                 Member of the ACM UMAP 2023 (International Conference on User Modeling, Adaptation and Personalization) International Program Committee and Demos, Theory, Opinion and Reflection and Late-Breaking Results Committee.  |  
            
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                 Senior Member of the ACM UMAP 2022 (International Conference on User Modeling, Adaptation and Personalization) International Program Committee and Demos, Theory, Opinion and Reflection and Late-Breaking Results, and Doctoral Consortium Committee.  |  
            
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                  Member of the CD-MAKE 2022 (International Cross Domain Conference for Machine Learning & Knowledge Extraction) International Program Committee.  |  
            
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                 Guest Associate Editor, Frontiers in Virtual Reality and Human Behaviour.   |  
            
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                 Associate Editor, Frontiers in Artificial Intelligence for Human Learning and Behavior Change.   |  
            
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                 Senior Member of the ACM UMAP 2021 (International Conference on User Modeling, Adaptation and Personalization) International Program Committee and Demos, Theory, Opinion and Reflection and Late-Breaking Results Committee.  |  
            
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               Board Member of the International Conference on Social Computing and Social Media @ HCI 2021.  |  
            
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                 Member of the ACM CHI 2020 (International Conference on Human Factors in Computing Systems) International Program Committee.  |  
            
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                 Member of the ACM UMAP 2020 (International Conference on User Modeling, Adaptation and Personalization) International Program Committee and Demos, Theory, Opinion and Reflection and Late-Breaking Results Committee.  |  
            
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                  Member of the CD-MAKE 2020 (International Cross Domain Conference for Machine Learning & Knowledge Extraction) International Program Committee.  |  
            
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               Board Member of the International Conference on Social Computing and Social Media @ HCI 2020.  |  
 
            
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                 Reviewer of the Frontiers in Psychology.   |  
            
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                  Guest Associate Editor, Frontiers in Artificial Intelligence, AI for Human Learning and Behavior Change.   |  
            
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                 Member of the ACM UMAP 2019 (International Conference on User Modeling, Adaptation and Personalization) International Program Committee and Demos, Theory, Opinion and Reflection and Late-Breaking Results Committee. (outstanding PC member)  |  
              
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                  Member of the ICSLE 2019 (International Conference on Smart Learning Environments) International Program Committee.  |  
            
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                  Member of the CD-MAKE 2019 (International Cross Domain Conference for Machine Learning & Knowledge Extraction) International Program Committee.  |  
              
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               Board Member of the International Conference on Social Computing and Social Media @ HCI 2019.  |  
 
              
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                 Reviewer of the User Modeling and User-Adapted Interaction (UMUAI) Journal.   |  
              
            
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               Reviewer of the book Personalized Human-Computer Interaction (2018) published by DeGruyter Oldenbourg, Germany.   |  
              
                
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               Member of the ACM UMAP 2018 (International Conference on User Modeling, Adaptation and Personalization) International Program Committee and Doctoral Consortium and Demo, Theory, Opinion and Reflection and Late-Breaking Results Committees.  |  
        
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               Member of the ACM IUI 2018 (International Conference on Intelligent User Interfaces) International Program Committee for Poster & Demo track.  |  
              
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                Member of the EC-TEL 2018 (European Conference on Technology Enhanced Learning) International Program Committee.  |  
              
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                Member of the WEBIST 2018 (International Conference on Web Information Systems and Technologies) International Program Committee.  |  
               
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                  Member of the ICSLE 2018 (International Conference on Smart Learning Environments) International Program Committee.  |  
              
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                  Member of the CD-MAKE 2018 (International Cross Domain Conference for Machine Learning & Knowledge Extraction) International Program Committee.  |  
              
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               Board Member of the International Conference on Social Computing and Social Media @ HCI 2018.  |  
 
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                  Member of the ACM UMAP 2017 (International Conference on User Modeling, Adaptation and Personalization) International Program Committee and Posters, Demos and Late Breaking Results Committee.  |  
             
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                Member of the ACM IUI 2017 (International Conference on Intelligent User Interfaces) International Program Committee and Demo & Posters Committee.  |  
             
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                  Member of the CD-MAKE 2017 (International Cross Domain Conference for Machine Learning & Knowledge Extraction) International Program Committee.  |  
             
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                  Member of the ICSLE 2017 (International Conference on Smart Learning Environments) International Program Committee.  |  
             
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                Member of the HUCAPP 2017 (International Conference on Human Computer Interaction Theory and Applications) International Program Committee.  |  
                    
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                Member of the WEBIST 2017 (International Conference on Web Information Systems and Technologies) International Program Committee.  |  
               
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                Board Member of the International Conference on Social Computing and Social Media @ HCI 2017.  |  
  
        
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                Member of the ICWL 2016 (International Conference on Web-based Learning) International Program Committee.  |  
       
        
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                  Member of the ACM UMAP 2016 (International Conference on User Modeling, Adaptation and Personalization) International Program Committee, and Doctoral Consortium and Posters, Demos and Late Breaking Results Committees.  |  
        
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                  Member of the ICSLE 2016 (International Conference on Smart Learning Environments) International Program Committee.  |  
        
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                 Member of the ACHI 2016 (International Conference on Advances in Computer-Human Interactions) International Program Committee.  |  
          
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                Member of the IHCI 2016 (Interfaces and Human Computer Interaction) Program Committee.  |  
           
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                Member of the WEBIST 2016 (International Conference on Web Information Systems and Technologies) International Program Committee.  |  
               
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                Member of the International Workshop on Semantic Big Data (SBD 2016), in conjunction with ACM SIGMOD 2016, Program Committee.  |  
   
           
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                 Member of the ITS 2015 (Internet Technologies and Society) Scientific Program Committee.  |  
            
                    
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                Member of the International Workshop on Semantic and Web (SaW 2015) Program Committee.  |  
           
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                  Reviewer of the Interacting with Computers Journal (IwC), Oxford University Press.   |  
               
               
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                Member of the IHCI 2015 (Interfaces and Human Computer Interaction) Program Committee.  |  
    
               
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                Member of the ICALT 2015 (International Conference on Advanced Learning Technologies) International Program Committee.  |  
               
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                  Program Committee of the SI on Social Media and Networks for Multimedia Content Management to be published in the International Journal of Virtual Communities and Social Networking (IJVCSN).   |  
               
              
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                  Member of the ICSLE 2015 (International Conference on Smart Learning Environments) International Program Committee.  |  
              
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                 Member of the KomIS 2015 (Knowledge Discovery meets Information Systems: Experiences and lessons learned dealing with real-life scenarios) Special Session, within the DATA 2015, International Program Committee.  |  
              
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                 Member of the ACHI 2015 (International Conference on Advances in Computer-Human Interactions) International Program Committee.  |  
              
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                 Member of the WEBIST 2015 (International Conference on Web Information Systems and Technologies) International Program Committee.  |  
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                  Reviewer of the Information Processing & Management Journal, Elsevier.   |  
             
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                 Member of the KomIS 2014 (Knowledge Discovery meets Information Systems: Experiences and lessons learned dealing with real-life scenarios) Special Session, within the DATA 2014, International Program Committee.  |  
             
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                 Member of the ITS 2014 (Internet Technologies and Society) Scientific Program Committee.  |  
           
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                Member of the ICWL 2014 (International Conference on Web-based Learning) International Program Committee.  |  
              
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                Member of the ICALT 2014 (International Conference on Advanced Learning Technologies) International Program Committee.  |  
           
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                Member of the IHCI 2014 (Interfaces and Human Computer Interaction) Program Committee.  |  
            
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                Member of the SMAP 2014 (Semantic and Social Media Adaptation and Personalization) Technical Program Committee.  |  
           
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               Editorial Board member of the Open Journal of Web Technologies (OJWT).  					 		
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               Member of the Human-Computer Interaction & Knowledge Discovery and Data Mining (HCI-KDD) Expert Network.  					 		        |   | 
                 
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                Member of the WEBIST 2014 (International Conference on Web Information Systems and Technologies) International Program Committee.  |  
           
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                Member of the ITS 2013 (Internet Technologies and Society) Scientific Program Committee.  |  
           
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               Reviewer of the Pacific Asia Journal of the Association for Information Systems (PAJAIS).  					 		
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               Member of the SS-HCI-KDD (Special Session on Human-Computer Interaction & Knowledge Discovery) – SouthCHI 2013, International Scientific Committee.  |  
            
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               Member of the ICALT 2013 (International Conference on Advanced Learning Technologies) International Program Committee.  |  
          
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               Member of the IHCI 2013 (Interfaces and Human Computer Interaction) Program Committee.  |  
           
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                 Reviewer of the Special Issue on Semantic Social Media Dynamics, International Journal of Semantic Web and Information Systems (IJSWIS).  |   | 
          
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			    Member of the ID&HCI 2013 (Interaction Design & Human-Computer Interaction Workshop) Program Committee.  |  
            
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                Member of the WEBIST 2013 (International Conference on Web Information Systems and Technologies) International Program Committee.  |  
            
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                Member of the SMAP 2013 (Semantic and Social Media Adaptation and Personalization) Technical Program Committee.  |  
           
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                Member of the ITS 2012 (Internet Technologies and Society) Scientific Program Committee.  |  
          
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                Member of the SMAP 2012 (Semantic and Social Media Adaptation and Personalization) Technical Program Committee.  |  
           
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                Member of the IHCI 2012 (Interfaces and Human Computer Interaction) Program Committee.  |  
            
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                Member of the ICALT 2012 (International Conference on Advanced Learning Technologies) International Program Committee.  |  
           
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                Member of the WEBIST 2012 (International Conference on Web Information Systems and Technologies) International Program Committee.  |  
           
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                Reviewer of the Transactions on Database Systems (TODS).   |  
           
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                Member of the IHCI 2011 (Interfaces and Human Computer Interaction) Program Committee.  |  
           
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                Member of the 1st European Workshop on HCI Design and Evaluation Program Committee.  |  
            
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                Reviewer of the Computer and Education International Journal, Elsevier.   |  
           
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                Reviewer of the International Journal of Vocational and Technical Education (IJVTE).   |  
          
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                Member of the SMAP 2011 (Semantic Media Adaptation and Personalization) Technical Program Committee.  |  
		
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				 Member of the ICALT 2011 (International Conference on Advanced Learning Technologies) International Program Committee.  |  
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                  Member of the MCIS 2010 (Mediterranean Conference on Information Systems) International Program Committee.  |  
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		          Member of the ICALT 2010 (International Conference on Advanced Learning Technologies) International Program Committee.  |  
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                  Reviewer of the ITAB 2009 (International Conference on Information Technology and Applications in Biomedicine).  |  
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                  Member of the mLIfe 2009 (mobile Life) International Program Committee.  |  
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                  Reviewer of the Encyclopedia of e-Business Development and Management in the Global Economy.   |  
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                Member of the ICALT 2009 (International Conference on Advanced Learning Technologies) International Program Committee.  |  
		  
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		       Reviewer of the Special Issue on Recommender Systems on the Web for ACM Transactions on the Web.   |  
		 
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		      Member of the CELDA 2008 (Cognition and Exploratory Learning in Digital Age) International Program Committee.  |  
		  
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		      Member of the Mobile Government Consortium International (mGCI).  |  
		 
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		      Member of the CELDA 2007 (Cognition and Exploratory Learning in Digital Age) International Program Committee.  |  
		 
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		      Editorial Review Board member of the International Journal of E-Government Research (IJEGR).   |  
		 
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		      Member of the EURO mGOV 2006 (mobile Government) International Program Committee (IPC).  |  
		 
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		      Member of the IRMA 2007 (Information Resources Management Association) International Program Committee.  |  
		  
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