Last 7 days
Bookmark and Share    
Full Text
Peer Reviewed
See detail"Getting on the same page" - How participants' reading aloud from an interactive tabletop facilitates joint game participation
Heuser, Svenja UL; Arend, Béatrice UL; Sunnen, Patrick UL

Scientific Conference (2021, July 01)

This paper addresses how adult participants in a multiparty serious game-activity (ORBIT project, see Sunnen et al. 2018) at an interactive tabletop (ITT) use reading aloud (Heuser et al. 2020) to co ... [more ▼]

This paper addresses how adult participants in a multiparty serious game-activity (ORBIT project, see Sunnen et al. 2018) at an interactive tabletop (ITT) use reading aloud (Heuser et al. 2020) to co-facilitate joint accessibility to interactionally relevant text information about the unfamiliar game they are engaging in. These so called ‘written informings’ displayed on the horizontal interface are designed to serve as a game-manual. Since the activity is new to the participants, they rely on these informings in order to jointly accomplish the game. We consider participants’ reading aloud as an interactional practice for participating in the interaction and getting each other ‘on the same page’. By verbalizing and thereby also emphasizing specific (parts of the) text at a specific point in the interaction, participants make written informings from the ITT interactionally relevant and mutually accessible within the group. [less ▲]

Detailed reference viewed: 34 (3 UL)
Full Text
See detailChronique de droit des marchés financiers
Conac, Pierre-Henri UL

in Revue des Sociétés (2021)

Detailed reference viewed: 26 (0 UL)
Full Text
Peer Reviewed
See detailLifelike Computing Systems
Stein, Anthony; Tomforde, Sven; Botev, Jean UL et al

in Proceedings of the Lifelike Computing Systems Workshop (LIFELIKE) (2021, July)

Detailed reference viewed: 35 (3 UL)
Full Text
Peer Reviewed
See detailTaming Reflection: An Essential Step Toward Whole-program Analysis of Android Apps
Sun, Xiaoyu; Li, Li; Bissyande, Tegawendé François D Assise UL et al

in ACM Transactions on Software Engineering and Methodology (2021), 30(3), 1-36

Android developers heavily use reflection in their apps for legitimate reasons. However, reflection is also significantly used for hiding malicious actions. Unfortunately, current state-of-the-art static ... [more ▼]

Android developers heavily use reflection in their apps for legitimate reasons. However, reflection is also significantly used for hiding malicious actions. Unfortunately, current state-of-the-art static analysis tools for Android are challenged by the presence of reflective calls which they usually ignore. Thus, the results of their security analysis, e.g., for private data leaks, are incomplete, given the measures taken by malware writers to elude static detection. We propose a new instrumentation-based approach to address this issue in a non-invasive way. Specifically, we introduce to the community a prototype tool called DroidRA, which reduces the resolution of reflective calls to a composite constant propagation problem and then leverages the COAL solver to infer the values of reflection targets. After that, it automatically instruments the app to replace reflective calls with their corresponding Java calls in a traditional paradigm. Our approach augments an app so that it can be more effectively statically analyzable, including by such static analyzers that are not reflection-aware. We evaluate DroidRA on benchmark apps as well as on real-world apps, and demonstrate that it can indeed infer the target values of reflective calls and subsequently allow state-of-the-art tools to provide more sound and complete analysis results. [less ▲]

Detailed reference viewed: 34 (2 UL)
Full Text
Peer Reviewed
See detailSecure Transmission in Cell-Free Massive MIMO With RF Impairments and Low-Resolution ADCs/DACs
Zhang, Xianyu; Liang, Tao; An, Kang et al

in IEEE Transactions on Vehicular Technology (2021), 70(9, Sept. 2021), 8937-8949

This paper considers the secure transmission in a cell-free massive MIMO system with imperfect radio frequency (RF) chains and low-resolution analog-to-digital converters (ADCs) and digital-to-analog ... [more ▼]

This paper considers the secure transmission in a cell-free massive MIMO system with imperfect radio frequency (RF) chains and low-resolution analog-to-digital converters (ADCs) and digital-to-analog converters (DACs) at both access points (APs) and legitimate users, where an active eavesdropper attempts to wiretap the confidential data. The Gaussian RF impairment model (GRFIM) and additive quantization noise model (AQNM) are used to evaluate the impacts of the RF impairments and low resolution ADCs/DACs, respectively. The analytical results of the linear minimum mean square error (MMSE) channel estimation show that there is nonzero floor on the estimation error with respect to the RF impairments, ADC/DAC precision and the pilot power of the eavesdropper which is different from the conventional case with perfect transceiver. Then, a tractable closed-form expression for the ergodic secrecy rate is obtained with respect to key system parameters, such as the antenna number per AP, the AP number, user number, quality factors of the ADC/DAC and the RF chain, pilot signal power of the eavesdropper, etc. Moreover, a compensation algorithm between the imperfect RF components and the inexpensive coarse ADCs/DACs is also presented. Finally, numerical results are provided to illustrate the efficiency of the achieved expressions and the devised algorithm, and show the effects of RF impairments and low resolution ADC/DAC on the secrecy performance. [less ▲]

Detailed reference viewed: 17 (1 UL)
Full Text
Peer Reviewed
See detailRepeatability and precision of different static deflection measurements on a real bridge-part under outdoor conditions in view of damage detection
Kebig, Tanja UL; Nguyen, Viet Ha UL; Bender, Michél et al

in Cunha, A.; Caetano, E. (Eds.) Proceedings of the 10th International Conference on Structural Health Monitoring of Intelligent Infrastructure, SHMII 10 (2021, July)

A large number of concrete bridges show increasing damage due to corrosion and fatigue. The traditional visual inspection and subsequent assessment of concrete bridges is carried out regularly by an ... [more ▼]

A large number of concrete bridges show increasing damage due to corrosion and fatigue. The traditional visual inspection and subsequent assessment of concrete bridges is carried out regularly by an experienced engineer. This type of inspection can be time-consuming, costly and leading to errors. Hence, there is a great interest in complementary, alternative and easy-to-implement methods for condition monitoring of bridges. The University of Luxembourg tested different approaches on a part of a real bridge. Various tests were performed in the healthy reference state, e.g. loading tests with a movable test load according to today’s standards. The measurements in the reference state were repeated several times under outdoor conditions to monitor and document the real temperature influence. Displacement transducers were set up in the vertical and horizontal directions. Simultaneously, a new approach was used for determining the deflection with a laser-based system, that measured the displacements in the bridge’s longitudinal direction by an oblique reflector panel under a well-defined angle. The data gained from the laser-based measurement system were compared to the data from classical displacement transducers. In general, the comparison of the two measuring systems shows quite similar results. [less ▲]

Detailed reference viewed: 89 (7 UL)
Full Text
Peer Reviewed
See detail𝑘-Pareto Optimality for Many-Objective Genetic Optimization
Ruppert, Jean; Aleksandrova, Marharyta UL; Engel, Thomas UL

Poster (2021, July)

Detailed reference viewed: 39 (2 UL)
Full Text
Peer Reviewed
See detailFederated Learning-based Scheme for Detecting Passive Mobile Attackers in 5G Vehicular Edge Computing
Boualouache, Abdelwahab UL; Engel, Thomas UL

in Annals of Telecommunications (2021)

Detecting passive attacks is always considered difficult in vehicular networks. Passive attackers can eavesdrop on the wireless medium to collect beacons. These beacons can be exploited to track the ... [more ▼]

Detecting passive attacks is always considered difficult in vehicular networks. Passive attackers can eavesdrop on the wireless medium to collect beacons. These beacons can be exploited to track the positions of vehicles not only to violate their location privacy but also for criminal purposes. In this paper, we propose a novel federated learning-based scheme for detecting passive mobile attackers in 5G Vehicular Edge Computing. We first identify a set of strategies that can be used by attackers to efficiently track vehicles without being visually detected. We then build an efficient Machine Learning (ML) model to detect tracking attacks based only on the receiving beacons. Our scheme enables Federated Learning (FL) at the edge to ensure collaborative learning while preserving the privacy of vehicles. Moreover, FL clients use a semi-supervised learning approach to ensure accurate self-labeling. Our experiments demonstrate the effectiveness of our proposed scheme to detect passive mobile attackers quickly and with high accuracy. Indeed, only 20 received beacons are required to achieve 95\% accuracy. This accuracy can be achieved within 60 FL rounds using 5 FL clients in each FL round. The obtained results are also validated through simulations. [less ▲]

Detailed reference viewed: 45 (10 UL)
Full Text
Peer Reviewed
See detailMoral Principles: Hedged, Contributory, Mixed
Knoks, Aleks UL

in Knoks, Aleks (Ed.) Deontic Logic and Normative Systems, 15th International Conference, DEON 2020/2021 (2021, July)

It's natural to think that the principles expressed by the statements "Promises ought to be kept" and "We ought to help those in need" are defeasible. But how are we to make sense of this defeasibility ... [more ▼]

It's natural to think that the principles expressed by the statements "Promises ought to be kept" and "We ought to help those in need" are defeasible. But how are we to make sense of this defeasibility? On one proposal, moral principles have hedges or built-in unless clauses specifying the conditions under which the principle doesn't apply. On another, such principles are contributory and, thus, do not specify which actions ought to be carried out, but only what counts in favor or against them. Drawing on a defeasible logic framework, this paper sets up three models: one model for each proposal, as well as a third model capturing a mixed view on principles that combines them. It then explores the structural connections between the three models and establishes some equivalence results, suggesting that the seemingly different views captured by the models are closer than standardly thought. [less ▲]

Detailed reference viewed: 39 (0 UL)
Full Text
Peer Reviewed
See detailUnlinkable Updatable Hiding Databases and Privacy-Preserving Loyalty Programs
Damodaran, Aditya Shyam Shankar UL; Rial, Alfredo UL

in Proceedings on Privacy Enhancing Technologies (2021, July), 2021(3), 95-121

Loyalty programs allow vendors to profile buyers based on their purchase histories, which can reveal privacy sensitive information. Existing privacy friendly loyalty programs force buyers to choose ... [more ▼]

Loyalty programs allow vendors to profile buyers based on their purchase histories, which can reveal privacy sensitive information. Existing privacy friendly loyalty programs force buyers to choose whether their purchases are linkable. Moreover, vendors receive more purchase data than required for the sake of profiling. We propose a privacy-preserving loyalty program where purchases are always unlinkable, yet a vendor can profile a buyer based on her purchase history, which remains hidden from the vendor. Our protocol is based on a new building block, an unlinkable updatable hiding database (HD), which we define and construct. HD allows the vendor to initialize and update databases stored by buyers that contain their purchase histories and their accumulated loyalty points. Updates are unlinkable and, at each update, the database is hidden from the vendor. Buyers can neither modify the database nor use old versions of it. Our construction for HD is practical for large databases. [less ▲]

Detailed reference viewed: 73 (18 UL)
Full Text
Peer Reviewed
See detailInvestigating the associations of trajectories of depressive symptoms and self-perceived health and incident dementia : an unsupervised machine learning approach.
Klee, Matthias UL; Leist, Anja UL

Poster (2021, July)

Background: Risk factors for dementia show inter-individually varying trajectories over the lifespan. However, risk factors have been mainly investigated with one time-point assessments. New research ... [more ▼]

Background: Risk factors for dementia show inter-individually varying trajectories over the lifespan. However, risk factors have been mainly investigated with one time-point assessments. New research suggests that certain risk factor trajectories are associated with increased risk of adverse cognitive outcomes (Demnitz et al., 2020 [https://doi.org/10.1101/2020.05.20.20106963]; Singh-Manoux et al., 2018 [https://doi.org/10.1016/j.jalz.2017.06.2637]). However, it remains unclear how sequential and simultaneous changes of risk factors alter the individual risk for developing dementia. Testing the joint contribution of trajectories of depressive symptoms and self-perceived health on incidence of dementia, we hypothesized that consistently poor as well as deteriorating trajectories increase the risk for incident dementia, and explored possible interactions of the trajectories. Method: A total of 5,326 respondents to the SHARE survey, mean age 73.9 years, and 6 complete follow-ups spanning ~13 years, answered the EURO-D depression scale, self-perceived health (SPH) (t1-t5), and self-reported dementia diagnosis at last follow-up (t6). To investigate the predictive ability of distinct longitudinal trajectories, we applied unsupervised statistical learning methods (K-means cluster modelling). Clusters indicated distinct risk factor trajectories, which were used as exposures in stepwise logistic regressions to predict incident dementia, controlling for age, gender, education, and country. Result: Cluster analysis revealed five distinct trajectories each for SPH and EURO-D, with varying dementia incidence. In stepwise logistic regressions, respondents with trajectories “consistently poor health” and “consistently high depression” showed elevated risk of dementia (OR = 4.02 [1.39, 14.75] and OR = 2.26 [1.03, 4.95], respectively) compared to the combined baseline risk for “consistently low depression” and “consistently good health”. Interactions were not significant. However, respondents with the combination of “consistently high depression” and “consistently poor health” showed increased risk (N = 246; 6.1% dementia). Conclusion: Applying unsupervised machine learning is helpful to incorporate longitudinal information on depressive symptoms and self-perceived health and model these risk factors longitudinally to test their contribution to explain incidence of dementia. The predictive ability of the trajectories of depressive symptoms and self-perceived health for dementia indicates the potential for improving the identification of people at risk for developing dementia in late life by exploiting trajectory information readily accessible through regular medical check-ups in old age. [less ▲]

Detailed reference viewed: 49 (6 UL)
Full Text
Peer Reviewed
See detailThe factor structure of mathematical abilities in Luxembourg’s national school monitoring: Its stability over elementary school and relations to, gender, language background, and SES
Sonnleitner, Philipp UL; Hornung, Caroline UL

Scientific Conference (2021, July)

Mathematics skills are the fundament of modern societies, especially those based on a knowledge-economy. The age of digitalization renders mathematics education even more crucial since it builds the ... [more ▼]

Mathematics skills are the fundament of modern societies, especially those based on a knowledge-economy. The age of digitalization renders mathematics education even more crucial since it builds the starting point for all STEM-related fields. Consequently, mathematics is at the core of numerous educational Large-Scale Assessments on international (e.g. PISA, TIMSS) or national level (e.g. NAEP, NEPS, SNSA). Although the underlying test development frameworks are most often multi-dimensional or hierarchical, psychometric analyses usually focus on a single latent factor that represents a rather vague general mathematical ability. How and to what extent this simplification affects educational studies that rely on these data remains unclear. The present study takes Luxembourg’s national school monitoring program ÉpStan as example to tackle this question and clarify the consequences. ÉpStan’s mathematics test is conducted annually in elementary school Grades 1, 3, and 5 and is comprised of around 50 to 70 items. Since ÉpStan captures competencies of all students biyearly, each analysis will be based on the full cohort (n > 5000). First, we will investigate whether the curriculum-based test framework for mathematics can psychometrically be represented in a related (multi-dimensional) confirmatory factor model including the domains numbers & operations and space & form. This will be done in Grades 1, 3, and 5. Second, we will study the factor model’s cross-sectional stability within each Grade (over three consecutive years) and longitudinal stability between Grades. Finally, we will study the factors’ relations to students’ cognitive and sociodemographic characteristics and compare the results with correlations found using the most widely used one-dimensional model of mathematical abilities. Based on the results, we will discuss implications not only for educational studies that often uncritically make use of large-scale assessment data, but also highlight the consequences for group-level feedback that is based on such assessments. [less ▲]

Detailed reference viewed: 51 (4 UL)
See detailFinance Crowd Analysis Project (FINCAP)
Wolff, Christian UL; Zhang, Lu UL

Report (2021)

More than 100 research teams (RTs) from around the world tested the same set of hypotheses on the same data. They worked independently and wrote an academic paper based on their findings. These reports ... [more ▼]

More than 100 research teams (RTs) from around the world tested the same set of hypotheses on the same data. They worked independently and wrote an academic paper based on their findings. These reports were be evaluated by more than 30 distinguished academics whom we refer to as peer evaluators (PEs). Their feedback was be passed on to the RTs so that they can revise their papers. The project coordinators will study the #fincap results to learn about the scientific process. They have committed ex-ante to a meta-science analysis which was frozen before any instructions and data were given to the RTs and PEs. This frozen “pre-analysis plan” was uploaded to the Open Science Framework on Monday, 2021-01-11. The project will lead to a peer-reviewed academic publication at high level. [less ▲]

Detailed reference viewed: 100 (16 UL)
Full Text
Peer Reviewed
See detailOn the Impact of Sample Duplication in Machine Learning based Android Malware Detection
Zhao, Yanjie; Li, Li; Wang, Haoyu et al

in ACM Transactions on Software Engineering and Methodology (2021), 30(3), 1-38

Detailed reference viewed: 31 (0 UL)
Full Text
Peer Reviewed
See detailGeneralized Chern numbers based on open system Green's functions
Farias, Maria Belen UL; Groenendijk, Solofo; Schmidt, Thomas UL

in New Journal of Physics (2021), 23

We present an alternative approach to studying topology in open quantum systems, relying directly on Green's functions and avoiding the need to construct an effective non-Hermitian (nH) Hamiltonian. We ... [more ▼]

We present an alternative approach to studying topology in open quantum systems, relying directly on Green's functions and avoiding the need to construct an effective non-Hermitian (nH) Hamiltonian. We define an energy-dependent Chern number based on the eigenstates of the inverse Green's function matrix of the system which contains, within the self-energy, all the information about the influence of the environment, interactions, gain or losses. We explicitly calculate this topological invariant for a system consisting of a single 2D Dirac cone and find that it is half-integer quantized when certain assumptions about the self-energy are made. Away from these conditions, which cannot or are not usually considered within the formalism of nH Hamiltonians, we find that such a quantization is usually lost and the Chern number vanishes, and that in special cases, it can change to integer quantization. [less ▲]

Detailed reference viewed: 33 (5 UL)
Full Text
Peer Reviewed
See detailSurface anchoring mediates bifurcation in nematic microflows within cylindrical capillaries
Paul, Steffen; Eric, Stellamanns; Sengupta, Anupam UL

in Physics of Fluids (2021), 33(072005), 072005-1-072005-13

Capillary microflows of liquid crystal phases are central to material, biological and bio-inspired systems. Despite their fundamental and applied significance, a detailed understanding of the stationary ... [more ▼]

Capillary microflows of liquid crystal phases are central to material, biological and bio-inspired systems. Despite their fundamental and applied significance, a detailed understanding of the stationary behavior of nematic liquid crystals (NLC-s) in cylindrical capillaries is still lacking. Here, using numerical simulations based on the continuum theory of Leslie, Ericksen, and Parodi, we investigate stationary NLC flows within cylindrical capillaries possessing homeotropic (normal) and uniform planar anchoring conditions. By considering the material parameters of the flow-aligning NLC, 5CB, we report that instead of the expected, unique director field monotonically approaching the alignment angle over corresponding Ericksen numbers (dimensionless number capturing viscous vs elastic effects), a second solution emerges at a threshold flow rate (or applied pressure gradient). We demonstrate that the onset of the second solution, a nematodynamic bifurcation yielding distinct director configurations at the threshold pressure gradient, can be controlled by the surface anchoring and the flow driving mechanism (pressure-driven or volume-driven). For homeotropic surface anchoring, this alternate director field orients against the alignment angle in the vicinity of the capillary center; while in the uniform planar case, the alternate director field extends throughout the capillary volume, leading to reduction of the flow speed with increasing pressure gradients. While the practical realization and utilization of such nematodynamic bifurcations still await systematic exploration, signatures of the emergent rheology have been reported by the authors previously within microfluidic environments, under both homeotropic and planar anchoring conditions. [less ▲]

Detailed reference viewed: 25 (2 UL)
Peer Reviewed
See detailThe sense of belonging in the context of migration and active ageing: The case of multicultural Luxembourg
Albert, Isabelle UL; Bemtgen, Nadia; Hoffmann, Martine et al

Scientific Conference (2021, July)

Migration is a life-changing transition and the establishment of new bonds in the receiving country constitutes an important developmental task. While feelings of belonging are closely linked to ... [more ▼]

Migration is a life-changing transition and the establishment of new bonds in the receiving country constitutes an important developmental task. While feelings of belonging are closely linked to subjective well-being, the feeling of not fitting in might be related to social exclusion and loneliness. Though social isolation is not bound to specific groups and ages, older migrants might be at a particular risk as recent studies suggest. The present study is part of the project PAN-VAL on active ageing in Luxembourg, financed by the Ministry of Family and Integration. Here, we focus on social embeddedness vs. social isolation of migrants and non-migrants living in the multicultural context of Luxembourg. Our aim is to identify facilitators and obstacles to participation in social activities, focusing in particular on the role of "sense of belonging" of older people to their place and country of residence. Applying a mixed-methods design, we will first focus on a national sample of N=1000 migrants and non-migrants 50+ living in Luxembourg who are asked about their family and friendship networks, leisure activities, sense of belonging to different entities (such as their neighborhood, municipality and country of residence) as well as their feelings of social isolation and loneliness. Secondly, we will draw on qualitative interviews in four selected municipalities contrasting active vs. non-active older migrants vs. non-migrants, exploring in more depth their experiences of belonging and social embeddedness. Results will be discussed in a life-span perspective, considering different developmental trajectories to belonging as a fundamental need of human beings. [less ▲]

Detailed reference viewed: 28 (1 UL)