Hello, I am an Associate Professor in the Department of Electrical and Computer Engineering, University of Patras, Greece. I am a member of the Interactive Technologies Laboratory and an expert member within the International Federation for Information Processing (IFIP) on the TC-13 Human-Computer Interaction Group.
My research is related to the design, development and evaluation of information systems with an emphasis in human-computer interaction, usable-security, human cognitive modeling and cultural heritage. Published research papers in top-ranked scientific venues, which received awards, (co-) supervised Ph.D. and M.Sc. students, and coordinated several EU-funded and National research projects. I am fluent in German, English and Greek.Email: fidas AT upatras.gr :: LinkedIn Profile: https://www.linkedin.com/in/fidas
National Project AILA :: #phishing #cybersecurity #artifical intelligence #legal advice #information systems
Artificial Intelligence-driven Framework and Legal Advice Tools for Phishing Prevention and Mitigation in Information Systems (€160,000, 2023-2025, Project Coordinator & Principal Investigator). Funding Agency: Hellenic Foundation for Research and Innovation (H.F.R.I.).
EU Project CREAMS :: #mixedreality #augmentedreality #virtualreality #artstudents #exhibitions
Scaffolding Creativity of Arts Students: Framework, Toolchain, and Educational Material on how to Create their Own Virtual Exhibitions (€382,644, 2022-2025, Project Coordinator & Principal Investigator). Funding Agency: European Commission. More info: CREAMS Project Website
National Project CogniX :: #electroencephalography #eyetracking #cognition
Electroencephalography and Eye Gaze-driven Framework for Intelligent and Real-Time Human Cognitive Modelling (€194,295, 2022-2024, Project Coordinator & Principal Investigator). Funding Agency: Hellenic Foundation for Research and Innovation (H.F.R.I.). More info: COGNIX Project Website
EU Project TRUSTID :: #cybersecurity #userauthentication #biometrics
Intelligent and Continuous Online Student Identity Management for Improving Security and Trust in European Higher Education Institutions (€291,310, 2021-2023, Project Coordinator & Principal Investigator). Funding Agency: European Commission. More info: TRUSTID Project Website
National Project DeAR Museum :: #mixedreality #virtualreality #culturalheritage
Development and production of augmented and virtual reality applications supporting narrative tours at the Tomato Industrial Museum in order to convey a personalized experience to the visitors of an old factory (€300,000, 2021-2023, Principal Investigator). Funding Agency: Research-Create-Innovate. More info: DeAR Museum Project Website
[Publications - July 2023] We are happy to announce that we will be participating at the 2nd International Conference of the ACM Greek SIGCHI Chapter. (CHIGREECE 2023) with three paper publications. The titles of our papers are: 1. Investigating Applicability Heuristics of Answer Set Programming in Game Development: Use Cases and Empirical Study. 2. Use of XR technologies for enhancing visitors' experience at industrial museums. 3. Methodologies and Ethical Considerations in Phishing Research: A Comprehensive Review.
[New Project & Research Funding - June 2023] We are excited for the approval of our research proposal, "AILA: Artificial Intelligence-driven Framework and Legal Advice Tools for Phishing Prevention and Mitigation in Information Systems", which has been granted funding of €160,000.00 from the Hellenic Foundation for Research and Innovation (H.F.R.I.) .
This project is a collaboration with the Law School of the Aristotle University of Thessaloniki. This project will explore the use of artificial intelligence (AI) and legal advice tools to prevent and mitigate phishing attacks in information systems. Our goal is to develop a comprehensive framework that can detect and respond to phishing attacks more effectively, ultimately improving the security and reliability of information systems.
As part of this project, we will be recruiting two PhD students to join our team. The successful candidates will have the opportunity to work on cutting-edge research, contribute to the development of a new cybersecurity framework, and collaborate with experts in artificial intelligence, law, and information systems.
[Publications - May 2023]
We are happy to announce that our lab will be participating at the 19th IFIP TC.13 International Conference on Human-Computer Interaction (INTERACT 2023) with three paper publications. The titles of our papers are:
1. Extending User Interaction with Mixed Reality through a Smartphone-based Controller
2. Exploring the Potential of Metaverse Apps for Real-World Applications: A Case Study with CALEND_AR
3. Influences of Cognitive Styles on EEG-based Activity: An Empirical Study on Visual Content Comprehension (Poster)
[Publication - May & July 2023]
We are delighted to announce the publication of the following two research papers which were conducted as part of the TRUST-ID project. It is a culmination of our efforts in the project, which has now successfully concluded.
a) Title: "Ensuring Academic Integrity and Trust in Online Learning Environments: A Longitudinal Study of an AI-Centered Proctoring System in Tertiary Educational Institutions", in Education Sciences. To learn more, please check out the full article https://doi.org/10.3390/educsci13060566.
Abstract: The credibility of online examinations in Higher Education is hardened by numerous factors and use-case scenarios. This paper reports on a longitudinal study, that spanned over eighteen months, in which various stakeholders from three European Higher Education Institutions (HEIs) participated, aiming to identify core threat scenarios experienced during online examinations, and to, accordingly, propose threat models, data metrics and countermeasure features that HEI learning management systems can embrace to address the identified threat scenarios. We also report on a feasibility study of an open-source intelligent and continuous student identity management system, namely TRUSTID, which implements the identified data metrics and countermeasures. A user evaluation with HEI students (n = 133) revealed that the TRUSTID system is resilient and effective against impersonation attacks, based on intelligent face and voice identification mechanisms, and scored well in usability and user experience. Aspects concerning the preservation of privacy in storing, retrieving and processing sensitive personal data are also discussed.
Abstract: The worldwide shift to distance learning at Higher Education Institutions (HEIs) during the COVID-19 global pandemic has raised several concerns about the credibility of online academic activities, especially regarding student identity management. Traditional online frameworks cannot guarantee the authenticity of the enrolled student, which requires instructors to manually verify their identities, a time-consuming task that compromises academic quality. This article presents a comprehensive review of existing efforts around continuous user identification, focusing on intelligent proctoring systems and automatic identification methods, as well as their applicability in this domain. We conclude that there is a clear need for continuous user identification technology by HEIs, but existing systems lack agile system integration models that combine many inputs, such as face, voice and behavioural data in a practical manner, and encounter numerous barriers related to data protection during implementation.
[Workshop Chair - April 2023] We are happy to announce the 1st International Workshop on Accessibility and Multimodal Interaction Design Approaches in Museums for People with Impairments, which is set to take place alongside the MobileHCI 2023 conference.
This workshop focuses on methods, tools, and techniques to design and
develop mobile museum applications for people with impairments. More
specifically, the research that will be presented will relate to technological
solutions that support museum visitors with visual, motor, dexterity, hearing,
and cognitive impairments. The rationale for the workshop is premised on the
significance of providing meaningful and engaging museum experiences to
visitors through mobile applications with customized interfaces adapted to
the characteristics of various groups of people with special needs.
Furthermore, the use of Mixed Reality, i.e., the combination of real and virtual
worlds, will be addressed in connection with the quest to foster access and
inclusion with regard to museums, and empowerment of people with
impairments. The workshop's primary goal is to bring together leading experts
to discuss the field's challenges and propose solutions concerning methods,
tools, and techniques in HCI, present their research on user requirements, and
system design to advance knowledge with the view to optimizing uses of
emerging technologies for enhancing cultural inclusion.
We are delighted to have Alan Dix as one of our invited speakers, who will share valuable insights and perspectives. We invite submissions from the research community to contribute their innovative ideas, empirical studies, and design approaches in this important domain. This workshop promises to be an engaging platform for knowledge exchange, collaboration, and the advancement of accessible and multimodal museum interaction design. [More info]
[Opening to Society Activity - March 2023] We are happy to share that the we hosted a group of 29 third-grade students from the High School - L.T. Farron , providing them with a unique opportunity to learn about our research in Brain Computer Interaction. As part of the visit, we demonstrated our state-of-the-art Mixed Reality apparatus, which received great interest and engagement from the young students.
[Publication - February 2023] We are excited to announce the publication of our research paper: Title: "A Review of EEG-Based User Authentication: Trends and Future Research Directions", in IEEE ACCESS. To learn more, please check out the full article https://10.1109/ACCESS.2023.3253026.
Abstract: Recently, the use of Electroencephalography (EEG) in scientific research on User Authentication (UA) has led to cutting-edge experiments that seek to identify and authenticate individuals based on their brain activity in particular usage scenarios. Utilizing EEG signals, derived from brain activity, might provide innovative solutions to contemporary security issues in traditional knowledge-based user authentication, including the threat of shoulder surfing. In this review paper, we analyze 108 different EEG-based user authentication experiments based on the following perspectives: a) the user experimental setup, with an emphasis on the applied EEG- protocols; b) the artificial intelligence techniques employed and finally c) the security and privacy preservation aspects. The reviewed papers cover a broad time frame from 1998 to 2022 and include various experimental protocols and algorithms used for classifying EEG signals. Additionally, the majority of the referenced works report findings from multiple experiments that incorporate distinct approaches and configurations. This leads to a discussion on best practices for EEG-based User Authentication and conclusions suggesting future research directions that consists, among others, of considering homomorphically encrypted biometric templates for information leakage prevention through federated learning approaches in decentralized architectures. We anticipate that the present literature review will provide a roadmap for future research by considering efficiently and effective EEG-based User Authentication methods while at the same time preserving privacy.
Summary: Scientific evidence underpins that humans differentiate in their inherent way to perceive and process visual information and that these differences in visual information processing immensely affect user experience and task execution in various application domains. This becomes even more relevant within virtual or mixed interaction contexts and applications which by definition necessitate from end-users to perform advanced visual information processing tasks that entails visual attention, search, processing and comprehension. In this talk we will present our recent research efforts which are focused on understanding the interplay among human cognition, visual behaviour and user experience within virtual and mixed reality interaction contexts. By doing this, we aim at building human cognition-centered user models based on users visual behaviour patterns that can serve as a basis for personalizing user interaction aiming to improve user experience within virtual or mixed reality applications.
[Publication - August 2022]
We are delighted that our longitudinal research that spanned over two years and embraced three public European healthcare organizations, with 169 participants,
has been published at ACM Transactions on Computing for Healthcare.
Title: "Security and Usability of a Personalized User Authentication Paradigm: Insights from a Longitudinal Study with Three Healthcare Organizations"
Abstract: This paper proposes a user-adaptable and personalized authentication paradigm for healthcare organizations, which anticipates to seamlessly reflect patients episodic and autobiographical memories to graphical and textual passwords aiming to improve the security strength of user-selected passwords and provide a positive user experience. We report on a longitudinal study that spanned over two years in which three public European healthcare organizations participated in order to design and evaluate the aforementioned paradigm. Three studies were conducted (N=169) with different stakeholders: i) a verification study aiming to identify existing authentication practices of the three healthcare organizations with diverse stakeholders (N=9); ii) a patient-centric feasibility study during which users interacted with the proposed authentication system (N=68); and iii) a human guessing attack study focusing on vulnerabilities among people sharing common experiences within location-aware images used for graphical passwords (N=92). Results revealed that the suggested paradigm scored high with regards to users' likeability, perceived security, usability and trust, but more importantly it assists the creation of more secure passwords. On the downside, the suggested paradigm introduces password guessing vulnerabilities from individuals sharing common experiences with the end-users. Findings are expected to scaffold the design of more patient-centric knowledge-based authentication mechanisms within nowadays dynamic computation realms.
[Publication - July 2022]
We are happy that our paper "Supporting People with Visual Impairments in Cultural Heritage: Survey and Future Research Directions" has been accepted at the International Journal of Human-Computer Interaction, 2022.
- Impact Factor: 4.920
Authors: Sylaiou S., Fidas C. (2022)- DOI: https://doi.org/10.1080/10447318.2022.2098930
Abstract: This literature review surveys published research that aims to foster blind and visually impaired (VI) people's engagement with cultural heritage. Fifty (50) papers are included in this survey, published between 2008 and 2021. They mostly focus on multisensory, multimodal, and interdisciplinary, ICT-based assistive human- centered computing approaches. These methods often optimize the user experience of VI-user's through an effort to gain an in-depth understanding of this special group's needs and accordingly design adaptive and adaptable interaction workflows. Moreover, several publications include user evaluations and empirical studies. Findings suggest that approaches tend to become more complex, multimodal, and multidisciplinary as time progresses. This leads to a discussion and conclusions suggesting future research directions in this domain. The proposed way forward relates to a synthesis of methodologies, scientific domains, and approaches into a more holistic, comprehensive, and synergetic model.
[Research Equipment - May 2022] We are happy to announce further extension of our laboratory research infrastructure by acquiring cutting-edge equipment with a total amount >50K. Among others, we obtained a state-of-the-art 41-channel Electroencephalography (EEG) device, a mixed-reality hands-free controllable headset and couple of eye-tracking lens. We aspire to design and conduct EEG multi-modal experiments to measure cognitive traits within innovative breakthrough interaction realms like MR/AR and VR and gesture control along with visual and/or acoustic stimuli. Moreover, we aim to develop and evaluate an electroencephalography based framework for intelligent real-time modeling of user cognitive intentions, thus laying the ground for ground-breaking advancements in various Brain Computer Interaction research fields. More info: COGNIX Project Website[view more]
[EU Project - December 2021] Happy to act as a Project Coordinator and Principal Investigator of the EU project CREAMS - Scaffolding Creativity of Arts Students: Framework, Toolchain, and Educational Material on how to Create their Own Virtual Exhibitions. The proposal was submitted in collaboration with the Aristotle University of Thessaloniki (Greece), Cognitive UX GmbH (Germany), the Cyprus University of Technology (Cyprus), the Shenkar College of Engineering, Design and Art (Israel), and the Norwegian University of Science and Technology (Norway).
[Research Project - July 2021]
Excited to receive a research grant of €194,295.00, from the
Hellenic Foundation for Research and Innovation (H.F.R.I.),
to Support Faculty Members & Researchers in the field of Engineering Sciences and Technology.
[Publications - June 2021] Happy about our three new paper publication at the 18th IFIP TC.13 International Conference on Human-Computer Interaction (INTERACT 2021), entitled "A Field Dependence-Independence Perspective on Eye Gaze Behavior within Affective Activities", "An Empirical Study of Picture Password Composition on Smartwatches" and "Understanding Insider Attacks in Personalized Picture Password Schemes".
[EU Project - March 2021] Ultra happy to act as a Project Coordinator and Principal Investigator of the EU project TRUSTID that has been approved by the European Commission with a total funding of €291,310. The proposal was submitted in collaboration with the University of Cyprus (Cyprus), the Institute of Systems and Robotics - University of Coimbra (Portugal) and Cognitive UX GmbH (Germany).
[Workshop at ACM UMAP 2021 - January 2021] We are looking forward to running the 3rd edition of our workshop APPS 2021 - Adaptive and Personalized Privacy and Security, in conjunction with ACM UMAP 2021. Our special focus in 2021 will be on challenges and opportunities related to the Covid-19 outbreak on ensuring security and privacy of sensitive data and secure user interactions in online systems such as challenges for online distance learning, the need for touchless authentication, e-Government, e-Commerce, etc.
[Publication - January 2021] Our paper entitled "From hot-spots towards experience-spots: Leveraging on users' sociocultural experiences to enhance security in cued-recall graphical authentication" has been accepted at the International Journal of Human-Computer Studies.
[New Position - November 2020] I am thankful for spending the last years at the Department of Cutlural Heritage Management and New Technologies of the University of Patras. Many thanks to all my colleagues and supporting staff for a fruitful and joyful collaboration. I am very happy to join the Electrical and Computer Engineering Department of the University of Patras. I look forward to work with my new colleagues and students.
[Guest Editor of Special Issue - November 2020] I am the Guest Editor, together with Dr. Stella Sylaiou and Dr. George Pavlidis, of the Special Issue "Mixed Reality in Culture and Heritage" at the Heritage Journal. Please download the Call for Papers (.pdf)
[Best Paper Award - October 2020] We received the prestigious UMUAI James Chen award for best paper of 2019, for our paper entitled "A cognition-centered personalization framework for cultural heritage content". The User Modeling and User Adapted Interaction (UMUAI) James Chen Award is bestowed annually to the author(s) of the best paper of the year. The award has been donated by the Chen family in commemoration of James R. Chen.
[Publication - March 2020] Our paper related to personalizing the user authentication process of information systems based on users' cross-cultural differences has been accepted at the ACM User Modeling, Adaptation and Personalization (UMAP 2020) papers' main program (23% acceptance rate). The work has been conducted in collaboration with the Shanghai Jiao Tong University.
[Project - December 2019]
I am enchanted that our project proposal "Development and production of augmented and virtual reality applications supporting narrative tours at the Tomato Industrial Museum "D. Nomikos" has been included for funding within the RESEARCH - CREATE - INNOVATE call. The proposal has been rated among the first 200 out of 2100 submissions (acceptance rate 10%).
The project proposes the production, presentation and promotion of a versatile cultural product that falls within the general context of the Museum's modern operation as cultural industry, thus linking academic research and innovation with entrepreneurship.
[Publication - December 2019] Our paper related to improving the estimation of graphical password strength based on the interplay between image content familiarity and gaze-behaviour on image hotspots has been accepted at the ACM Intelligent User Interfaces (IUI 2020) papers' main program (16% acceptance rate).
[Publication - November 2019] New paper accepted at the IEEE BigData 2019 conference, entitled "The SERUMS tool-chain: Ensuring Security and Privacy of Medical Data in Smart Patient-Centric Healthcare Systems".
[Paper Presentation at ACM WI 2019 - October 2019] I enjoyed participating at the ACM Web Intelligence 2019 conference, and presenting our two papers entitled "Eye Tracking based Cognitive-Centered User Models" and "I Recall this Picture": Understanding Picture Password Selections based on Users' Sociocultural Experiences". I also had the opportunity to meet other researchers and exchange interesting ideas for research.
[Editorial Board - September 2019] I am glad to join the Editorial Board of Heritage (https://www.mdpi.com/journal/heritage), a peer-reviewed and open access journal, covering all aspects of cultural and natural heritage science. The preliminary aims and topics are given at: https://www.mdpi.com/journal/heritage/about.
[New Publications - August 2019] Two papers accepted at ACM Web Intelligence 2019, entitled "Eye Tracking based Cognitive-Centered User Models" and "I Recall this Picture": Understanding Picture Password Selections based on Users' Sociocultural Experiences"
[Shanghai Jiao Tong University - May 2019] I was very delighted to visit the School of Design, Shanghai Jiao Tong University in the context of Erasmus+ International Credit Mobility Programme (KA107). I have been giving lectures for bachelor, master and doctoral students and discussed further research opportunities.
[New Publication - May 2019] Paper accepted at the IFIP TC.13 International Conference on Human-Computer Interaction â€“ INTERACT 2019, entitled "Influences of Mixed Reality and Human Cognition on Picture Passwords: An Eye Tracking Study"
[Guest Editor of Special Issue - April 2019]
I am the Guest Editor of the Special Issue "Virtual Reality and Their Application in Cultural Heritage" at the Applied Sciences Journal, Impact Factor 2.217
Submissions Deadline: 29 February 2020. Please download the Call for Papers (.pdf)
[New Publication - March 2019] Paper accepted at ACM SIGCHI UMAP 2019, entitled "On the Accuracy of Eye Gaze-driven Classifiers for Predicting Image Content Familiarity in Graphical Passwords"
[New EU H2020 Project - February 2019] I am happy to participate in the EU Horizon 2020 Serums project aiming to apply a User-centered Design process for defining new methods and tools for patient-centric user authentication
[Workshop Co-Organizer - January 2019] I am Co-Organizer, together with Dr. Marios Belk, Dr. Elias Athanasopoulos, and Dr. Andreas Pitsillides, of the First International Workshop on Adaptive and Personalized Privacy and Security (APPS 2019), in conjunction with the ACM User Modeling, Adaptation and Personalization (UMAP 2019) conference. Submission due date: March 13, 2019
[Guest Co-Editor - December 2018] I am Guest Co-Editor, together with Dr. Stella Sylaiou, for the Special Issue on ICT for Culture and Tourism at the International Journal of Computational Methods in Heritage Science (IJCMHS). Submission due date: December 20, 2018
[Invited Talk - November 2018] "Human Cognition, Visual Behavior and User Experience in Virtual / Mixed Reality Applications: Case Studies and Interaction Effects", VR@GR: Virtual Reality â€“ Research and Applications in Greece today, held at the Onassis Stegi.
[New Publication - November 2018] Journal paper accepted at User Modeling and User-Adapted Interaction (UMUAI), entitled "A cognition-centered personalization framework for cultural heritage content"
[New Publication - November 2018] Journal paper accepted at ACM Journal on Computing and Cultural Heritage (JOCCH), entitled "Do game designersâ€™ decisions related to visual activities affect knowledge acquisition in cultural heritage games? An evaluation from a human cognitive processing perspective"
[Invited Talk - May 2018] I enjoyed coming back to the University of Cyprus in the context of Erasmus+ Staff Mobility for Teaching Programme. During my stay I had the opportunity to meet my former colleagues and friends and exchange interesting ideas for research. I was also honored to give a talk at the Computer Science Colloquium Series at UCY and give seminars to Ph.D., M.Sc. and B.Sc. students on topics related to information systems, cultural heritage and usable security.
[Publication - April 2018] Congrats to Argyris Constantinides for his first regular paper at ACM SIGCHI UMAP 2018 concerning his Ph.D. thesis. The paper is entitled "On Cultural-centered Adaptive Graphical Passwords: Improving Password Memorability based on Users' Retrospective Memories". Wishes for many more success.
[Publication - April 2018] Paper accepted at ACM SIGCHI Eye Tracking Research & Applications (ETRA 2018), entitled "Towards Gaze-Based Quantification of the Security of Graphical Authentication Schemes"
[Invited Talk - March 2018] Invited talk, "Human-Centered Design and Evaluation of Digitized Cultural Heritage Experiences", at the 4th Thematic Seminar on "Digitization of Monuments and Archaeological Sites" in the context of the European Project "Collaborative Digitization of Natural and Cultural Heritage, CD-ETA" of the Programme "INTERREG EUROPE".
[Publication - February 2018] Journal paper accepted at the International Journal of Human-Computer Studies, entitled "Effects of Mixed-Reality on Players' Behaviour and Immersion in a Cultural Tourism Game: A Cognitive Processing Perspective"
[Publication - December 2017] Full paper accepted at ACM SIGCHI 2018, entitled "Influences of Human Cognition and Visual Behavior on Password Security during Picture Password Composition"
[Publication - December 2017] Paper accepted for inclusion in the ACM SIGCHI IUI 2018 Papers' Programme, entitled "Eye Gaze-driven Prediction of Cognitive Differences during Graphical Password Composition"
[Publication - April 2017] Paper accepted at ACM SIGCHI UMAP 2017, entitled "Using Eye Gaze Data and Visual Activities to Infer Human Cognitive Styles: Method and Feasibility Studies"
In this work, we have designed and developed CogniKit, an extensible tool for human cognitive modeling. It is based on the analysis, classification and visualization of eye tracking data such as gaze points, fixation count and duration, saccades, gaze transition and stationary entropy, heat maps, areas of interests, etc. These are further processed, analyzed and classified for detecting higher level human cognitive factors such as cognitive processing styles and abilities. CogniKit comprises of two main components: i) a software application that collects and processes low- and high-level eye gaze data metrics in real-time; and ii) an extensible interactive workbench for storing, analyzing, classifying and visualizing the collected eye gaze data.
Mixed reality technologies embrace hand gesture-based interaction modalities, which can be leveraged by picture passwords, as they require users to draw secret gestures on a background image. In this work, we have designed and developed HoloPass, a novel mixed reality application that utilizes the Microsoft HoloLens device that allows users to directly interact with picture-based holograms in order to perform user authentication tasks. The current prototype was developed in Unity 3D, using C# and Microsoft's Mixed Reality Toolkit for HoloLens, and follows implementation guidelines of Microsoft Windows 10 Picture Gesture Authentication in which users draw three secret gestures on a background image that acts as a cue.
This work aims at scaffolding end-users in improving the security of graphical passwords through a playful interaction design in mixed reality. For doing so, we elaborated on a playful interaction de-sign framework and developed, based on it, an experimental mixed reality (MR) application that deployed multi-modal and playful user interaction experiences. A user evaluation woth 30 participants revealed that introducing playful characteristics in the design of MR graphical passwords had a catalyst effect on the security of user generated passwords and simultaneously affected significantly end-users' perceptions and understanding related to security semantics of graphical passwords.
Assistant Professor (2016-2020), Tenure-track Lecturer (2013-2016) at the Department of Cultural Heritage and New Technologies, University of Patras
I am always happy to discuss with prospective students new research endeavors in the areas of Information Systems and Culture, Modelling Human Cognition in Interactive Systems, and Usable Security. If you are interested to discuss your research idea please don't hesitate to contact me at fidas AT upatras.grSuggested Topics for Ph.D.