Use of vitamin D supplements during infancy in an international feeding trial

in Public Health Nutrition (2014), 17(4), 810-822

To examine the use of vitamin D supplements during infancy among the participants in an international infant feeding trial. Longitudinal study.

User Experience Challenges for Designing Computer-Based Assessments

Poster (2019, June 12)

User Experience Design for Cybersecurity & Privacy: addressing user misperceptions of system security and privacy

Doctoral thesis (2022)

The increasing magnitude and sophistication of malicious cyber activities by various threat actors poses major risks to our increasingly digitized and inter-connected societies. However, threats can also ... [more ▼]

The increasing magnitude and sophistication of malicious cyber activities by various threat actors poses major risks to our increasingly digitized and inter-connected societies. However, threats can also come from non-malicious users who are being assigned too complex security or privacy-related tasks, who are not motivated to comply with security policies, or who lack the capability to make good security decisions. This thesis posits that UX design methods and practices are necessary to complement security and privacy engineering practices in order to (1) identify and address user misperceptions of system security and privacy; and (2) inform the design of secure systems that are useful and appealing from end-users’ perspective. The first research objective in this thesis is to provide new empirical accounts of UX aspects in three distinct contexts that encompass security and privacy considerations, namely: cyber threat intelligence, secure and private communication, and digital health technology. The second objective is to empirically contribute to the growing research domain of mental models in security and privacy by investigating user perceptions and misperceptions in the afore-mentioned contexts. Our third objective is to explore and propose methodological approaches to incorporating users’ perceptions and misperceptions in the socio-technical security analyses of systems. Qualitative and quantitative user research methods with experts as well as end users of the applications and systems under investigation were used to achieve the first two objectives. To achieve the third objective, we also employed simulation and computational methods. Cyber Threat Intelligence: CTI sharing platforms Reporting on a number of user studies conducted over a period of two years, this thesis offers a unique contribution towards understanding the constraining and enabling factors of security information sharing within one of the leading CTI sharing platforms, called MISP. Further, we propose a conceptual workflow and toolchain that would seek to detect user (mis)perceptions of key tasks in the context of CTI sharing, such as verifying whether users have an accurate comprehension of how far information travels when shared in a CTI sharing platform, and discuss the benefits of our socio-technical approach as a potential security analysis tool, simulation tool, or educational / training support tool. Secure & Private Communication: Secure Email We propose and describe multi-layered user journeys, a conceptual framework that serves to capture the interaction of a user with a system as she performs certain goals along with the associated user beliefs and perceptions about specific security or privacy-related aspects of that system. We instantiate the framework within a use case, a recently introduced secure email system called p≡p, and demonstrate how the approach can be used to detect misperceptions of security and privacy by comparing user opinions and behavior against system values and objective technical guarantees offered by the system. We further present two sets of user studies focusing on the usability and effectiveness of p≡p’s security and privacy indicators and their traffic-light inspired metaphor to represent different privacy states and guarantees. Digital Health Technology: Contact Tracing Apps Considering human factors when exploring the adoption as well as the security and privacy aspects of COVID-19 contact tracing apps is a timely societal challenge as the effectiveness and utility of these apps highly depend on their widespread adoption by the general population. We present the findings of eight focus groups on the factors that impact people’s decisions to adopt, or not to adopt, a contact tracing app, conducted with participants living in France and Germany. We report how our participants perceived the benefits, drawbacks, and threat model of the contact tracing apps in their respective countries, and discuss the similarities and differences between and within the study groups. Finally, we consolidate the findings from these studies and discuss future challenges and directions for UX design methods and practices in cybersecurity and digital privacy. [less ▲]

User Experience: a concept without consensus? Exploring practitioners' perspectives through an international survey.

in Computers in Human Behavior (2015), (43), 35-48

For more than a decade, User Experience (UX) has grown into a core concept of Human–Computer Inter- action (HCI). Practitioners and researchers from a wide range of disciplines are daily working with this ... [more ▼]

For more than a decade, User Experience (UX) has grown into a core concept of Human–Computer Inter- action (HCI). Practitioners and researchers from a wide range of disciplines are daily working with this concept. However, despite many attempts to understand, define and scope UX, one may still wonder whether a consensus has been reached on this concept. In a willingness to address the complexity of this research topic and bring the concept of UX to maturity, a replication of an international survey has been conducted. The main goal of the present study is to get a better understanding of practitioners’ view- points on the notion of UX and to analyze potential evolutions over time in the understanding and prac- tical use of the concept. As both practical and theoretical implications of UX are of the greatest importance for whoever designs interactive systems, the exploration of practitioners’ perspectives is a valuable step toward continual improvement of UX activities. The present survey has been conducted amongst 758 practitioners and researchers from 35 nationalities. It allows to better understand how this concept is understood and used throughout the world. Amongst interesting results, important differences were observed according to the geographical location and background of the respondents. [less ▲]

User Required? On the Value of User Research in the Digital Humanities

in Linköping Electronic Conference Proceedings (2015, August 26), (116), 63-74

Although computational tools play an increasingly important role in the humanities, adoption of tools by scholars does not always reach its potential. One approach to this problem is user research to ... [more ▼]

Although computational tools play an increasingly important role in the humanities, adoption of tools by scholars does not always reach its potential. One approach to this problem is user research to uncover the needs of the users. However, it is uncertain whether such user requirements can be generalized to a wider group of humanities scholars, and whether users are able to explicate their requirements for methodological innovation. We ask what the role of user research is in the Digital Humanities by discussing gathered user requirements for two projects. We categorized the requirements as within- or out-of-scope of the projects’ goals, and found a tension between the specificity of humanities’ research methods, and generalizability for a broader applicable tool. With the out-of-scope requirements we are able to map the wider research workflow, showing DH tools will most likely take a spot in the wider workflow, and that it is infeasible to create a tool for the entire workflow that is generic enough for a larger user group. However, the within-scope requirements led to features that were sufficiently generic for the tool to be adopted, also for unintended purposes. These insights show user research has a clear benefit for DH projects. [less ▲]

User requirements in ICT-based social media use: Acceptance of a virtual coach

Scientific Conference (2011)

User Scheduling and Power Allocation for Precoded Multi-Beam High Throughput Satellite Systems With Individual Quality of Service Constraints

in IEEE Transactions on Vehicular Technology (Early Access) (2022)

For extensive coverage areas, multi-beam high throughput satellite (HTS) communication is a promising technology that plays a crucial role in delivering broadband services to many users with diverse ... [more ▼]

For extensive coverage areas, multi-beam high throughput satellite (HTS) communication is a promising technology that plays a crucial role in delivering broadband services to many users with diverse Quality of Service (QoS) requirements. This paper focuses on multi-beam HTS systems where all beams reuse the same spectrum. In particular, we propose a novel user scheduling and power allocation design capable of providing guarantees in terms of the individual QoS requirements while maximizing the system throughput under a limited power budget. Precoding is employed in the forward link to mitigate mutual interference among the users in multiple-access scenarios over different coherence time intervals. The combinatorial optimization structure from user scheduling requires an extremely high cost to obtain the global optimum even when a reduced number of users fit into a time slot. Therefore, we propose a heuristic algorithm yielding a good trade-off between performance and computational complexity, applicable to a static operation framework of geostationary (GEO) satellite networks. Although the power allocation optimization is signomial programming, non-convex on a standard form, the solution can be lower bounded by the global optimum of a geometric program with a hidden convex structure. A local solution to the joint user scheduling and power allocation problem is consequently obtained by a successive optimization approach. Numerical results demonstrate the effectiveness of our algorithms on GEO satellite networks by providing better QoS satisfaction combined with outstanding overall system throughput. [less ▲]

User Scheduling for Coordinated Dual Satellite Systems with Linear Precoding

in International Communications Conference, Budapest 2013 (2013)

User Scheduling in Cooperative Satellite Systems

in Cooperative and Cognitive Satellite Systems (2015)

User selection for massive MIMO under line-of-sight propagation

in IEEE Open Journal of the Communications Society (2022)

This paper provides a review of user selection algorithms for massive multiple-input multiple-output (MIMO) systems under the line-of-sight (LoS) propagation model. Although the LoS propagation is ... [more ▼]

This paper provides a review of user selection algorithms for massive multiple-input multiple-output (MIMO) systems under the line-of-sight (LoS) propagation model. Although the LoS propagation is extremely important to some promising technologies, like in millimeter-wave communications, massive MIMO systems are rarely studied under this propagation model. This paper fills this gap by providing a comprehensive study encompassing several user selection algorithms, different linear precoders and simulation setups, and also considers the effect of partial channel state information (CSI). One important result is the existence of practical cases in which the LoS propagation model may lead to significant levels of interference among users within a cell; these cases are not satisfactorily addressed by the existing user selection algorithms. Motivated by this issue, a new user selection algorithm based on inter-channel interference (ICI) called ICI-based selection (ICIBS) is proposed. Unlike other techniques, the ICIBS accounts for the ICI in a global manner, thus yielding better results, especially in cases where there are many users interfering with each other. In such scenarios, simulation results show that when compared to the competing algorithms, the proposed approach provided an improvement of at least 10.9% in the maximum throughput and 7.7% in the 95%-probability throughput when half of the users were selected. [less ▲]