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See detailMind the gap: Robotic Mission Planning Meets Software Engineering
Askarpour, Mehrnoosh; Menghi, Claudio UL; Belli, Gabriele et al

in Proceedings of the 8th International Conference on Formal Methods in Software Engineering (2020)

In the context of robotic software, the selection of an appropriate planner is one of the most crucial software engineering decisions. Robot planners aim at computing plans (i.e., blueprint of actions) to ... [more ▼]

In the context of robotic software, the selection of an appropriate planner is one of the most crucial software engineering decisions. Robot planners aim at computing plans (i.e., blueprint of actions) to accomplish a complex mission. While many planners have been proposed in the robotics literature, they are usually evaluated on showcase examples, making hard to understand whether they can be effectively (re)used for realising complex missions, with heterogeneous robots, and in real-world scenarios. In this paper we propose ENFORCE, a framework which allows wrapping FM-based planners into comprehensive software engineering tools, and considers complex robotic missions. ENFORCE relies on (i) realistic maps (e.g, fire escape maps) that describe the environment in which the robots are deployed; (ii) temporal logic for mission specification; and (iii) Uppaal model checker to compute plans that satisfy mission specifications. We evaluated ENFORCE by analyzing how it supports computing plans in real case scenarios, and by evaluating the generated plans in simulated and real environments. The results show that while ENFORCE is adequate for handling single-robot applications, the state explosion still represents a major barrier for reusing existing planners in multi-robot applications. [less ▲]

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See detailSequential Temporary and Permanent Control of Boolean Networks.
Su, Cui; Pang, Jun UL

in Proceedings of the 18th International Conference on Computational Methods in Systems Biology (CMSB) (2020)

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See detailBorder-Making and its Consequences: A Global Overview.
Venken, Machteld UL; Fellner, Astrid; Dorfman, Adriana et al

in Eurasia Border Review (2020), 10(1), 59-69

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See detailIEEE Workshop on Parallel / Distributed Combinatorics and Optimization (PDCO 2020)
Danoy, Grégoire UL; Baz, Didier El; Boyer, Vincent et al

in 2020 IEEE International Parallel and Distributed Processing Symposium Workshops, IPDPSW 2020, New Orleans, LA, USA, May 18-22, 2020 (2020)

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See detailSecurity and Privacy in Resource-Constrained Devices
Chiara, Pier Giorgio UL

in CEUR Workshop Proceedings (2020), 2598

Recent adversarial attacks have been shown IoT devices weaknesses due to their limited computing power. Given also their ubiquitous presence, lower costs and limitations in keeping security measures up ... [more ▼]

Recent adversarial attacks have been shown IoT devices weaknesses due to their limited computing power. Given also their ubiquitous presence, lower costs and limitations in keeping security measures up-todate, resource-constrained devices represent a growing risk for the security of IT infrastructure. The scope of the research is to investigate the weaknesses of resource-constrained IoT devices. The methodology for the investigation is the legal analysis of existing legal frameworks regulating IoT cybersecurity and data security; afterwards it will be carried out a critical evaluation of the existing best practices. This critical analysis should face the twofold challenge of increasing transparency and trust in resource-constrained systems. Users and companies are two faces of the same coin: accountability of data collectors and user awareness are crucial in the security and data protection debate. Thus, a comprehensive overview of the relevant legal frameworks and guidelines would increase the understanding of risks of the users, whilst data controllers (especially of small and medium enterprises) may have an instrument to implement properly security measures. [less ▲]

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See detailCramer-Rao Bound on DOA Estimation of Finite Bandwidth Signals Using a Moving Sensor
Arora, Aakash UL; Mysore Rama Rao, Bhavani Shankar UL; Ottersten, Björn UL

in Proc. 2020 IEEE International Conference on Acoustics, Speech, and Signal Processing (ICASSP) (2020)

In this paper, we provide a framework for the direction of arrival (DOA) estimation using a single moving sensor and evaluate performance bounds on estimation. We introduce a signal model which captures ... [more ▼]

In this paper, we provide a framework for the direction of arrival (DOA) estimation using a single moving sensor and evaluate performance bounds on estimation. We introduce a signal model which captures spatio-temporal incoherency in the received signal due to sensor motion in space and finite bandwidth of the signal, hitherto not considered. We show that in such a scenario, the source signal covariance matrix becomes a function of the source DOA, which is usually not the case. Due to this unknown dependency, traditional subspace techniques cannot be applied and conditions on source covariance needs to imposed to ensure identifiability. This motivates us to investigate the performance bounds through the Cramer-Rao Lower Bounds (CRLBs) to set benchmark performance for future estimators. This paper exploits the signal model to derive an appropriate CRLB, which is shown to be better than those in relevant literature. [less ▲]

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See detailExamining the Interplay of Generalized and Personal Views on Aging on Physical and Mental Health Across 2.5 Years
Brothers, Allyson; Kornadt, Anna Elena UL; Nehrkorn-Bailey, Abigail et al

in Innovation in Aging (2020), 4(Supplement_1), 588-588

It remains unknown how distinct types of views on aging (VoA) are related to one another, and to aging outcomes. We used a latent-variable structural equation model to test the hypothesis that generalized ... [more ▼]

It remains unknown how distinct types of views on aging (VoA) are related to one another, and to aging outcomes. We used a latent-variable structural equation model to test the hypothesis that generalized views on aging (assessed as Age Stereotypes (AS)) would influence personal views on aging (assessed as Self-Perceptions of Aging (SPA)), which in-turn would influence later physical and mental health. Data came from a longitudinal survey on VoA (N= 537, MageT1 = 64.13, age rangeT1 = 40-98). As expected, SPA mediated the effect of AS on physical (loss-SPA: β = .23, p< .001; gain-SPA: β = .06, p< .001; R2 = .62) and mental health (loss-SPA: β = .13, p< .001; gain-SPA: β = .03, p< .01, ; R2 = .31). Congruent with theoretical assumptions, our findings provide empirical support for a directional pathway by which generalized views on aging affect health outcomes via personal views of aging. [less ▲]

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See detailSocial Roles, Subjective Age, and Gender: Exploring the Links in Later Life
Kornadt, Anna Elena UL

in Innovation in Aging (2020), 4(Supplement_1), 556-556

Subjective age (SA) is strongly linked to positive developmental outcomes and successful aging. The social roles people assume are supposed to impact SA, since they incorporate age-graded social ... [more ▼]

Subjective age (SA) is strongly linked to positive developmental outcomes and successful aging. The social roles people assume are supposed to impact SA, since they incorporate age-graded social experiences and age-stereotypic role expectations. Social roles are also strongly gendered, providing the opportunity to understand gender-specific processes of SA. This study investigates a broad range of social roles and their relation to older men and women’s SA in later life. N = 285 participants aged 50 to 86 years (Mage = 65.04, SD = 8.88) reported on 19 social roles and their SA. Higher commitment to social roles of continued development and engagement was related to a younger subjective age, above and beyond sociodemographic variables, physical and mental health, but only for younger men. Commitment to family roles was related to a younger subjective age only for older men. Implications for the gender-specific understanding of antecedents of SA are discussed. [less ▲]

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See detailGesonderte Ruhestätten für besondere Tote: Soldatengräber und Garnisonsfriedhöfe unter besonderer Berücksichtigung der Entwicklung in Luxemburg
Kolnberger, Thomas UL

in Loew, Benedikt; Thewes, Guy; Klauck, Hans Peter (Eds.) Intra muros - Infrastruktur und Lebensalltag in Festungen - Einrichtungen der Fürsorge (2020)

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See detailSMRL: A Metamorphic Security Testing Tool for Web Systems
Mai, Xuan Phu UL; Göknil, Arda; Pastore, Fabrizio UL et al

in 2020 IEEE/ACM 42nd International Conference on Software Engineering (2020)

We present a metamorphic testing tool that alleviates the oracle problem in security testing. The tool enables engineers to specify metamorphic relations that capture security properties of Web systems ... [more ▼]

We present a metamorphic testing tool that alleviates the oracle problem in security testing. The tool enables engineers to specify metamorphic relations that capture security properties of Web systems. It automatically tests Web systems to detect vulnerabilities based on those relations. We provide a domain-specific language accompanied by an Eclipse editor to facilitate the specification of metamorphic relations. The tool automatically collects the input data and transforms the metamorphic relations into executable Java code in order to automatically perform security testing based on the collected data. The tool has been successfully evaluated on a commercial system and a leading open source system (Jenkins). Demo video: https://youtu.be/9kx6u9LsGxs. [less ▲]

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See detailL’édition de chartes à Luxembourg: de l’érudition aux nouvelles technologies (et vice-versa?)
Salemme, Timothy UL

in Bendheim, Amelie (Ed.) Tagungsband Mittelalter zwischen Faszination und Fortschritt (2020)

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See detailMaking Encryption Feel Secure: Investigating how Descriptions of Encryption Impact Perceived Security
Distler, Verena UL; Lallemand, Carine UL; Koenig, Vincent UL

in The 5th European Workshop on Usable Security (EuroUSEC 2020) (2020)

When communication about security to end users is ineffective, people frequently misinterpret the protection offered by a system. The discrepancy between the security users perceive a system to have and ... [more ▼]

When communication about security to end users is ineffective, people frequently misinterpret the protection offered by a system. The discrepancy between the security users perceive a system to have and the actual system state can lead to potentially risky behaviors. It is thus crucial to understand how security perceptions are shaped by interface elements such as text-based descriptions of encryption. This article addresses the question of how encryption should be described to non-experts in a way that enhances perceived security. We tested the following within-subject variables in an online experiment (N=309): a) how to best word encryption, b) whether encryption should be described with a focus on the process or outcome, or both c) whether the objective of encryption should be mentioned d) when mentioning the objective of encryption, how to best describe it e) whether a hash should be displayed to the user. We also investigated the role of context (between subjects). The verbs “encrypt” and “secure” performed comparatively well at enhancing perceived security. Overall, participants stated that they felt more secure not knowing about the objective of encryption. When it is necessary to state the objective, positive wording of the objective of encryption worked best. We discuss implications and why using these results to design for perceived lack of security might be of interest as well. This leads us to discuss ethical concerns, and we give guidelines for the design of user interfaces where encryption should be communicated to end users. [less ▲]

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See detailCPSDebug: a tool for explanation of failures in cyber-physical systems
Bartocci, Ezio; Manjunath, Niveditha; Mariani, Leonardo et al

in CPSDebug: a tool for explanation of failures in cyber-physical systems (2020)

Debugging Cyber-Physical System models is often challenging, as it requires identifying a potentially long, complex and heterogenous combination of events that resulted in a violation of the expected ... [more ▼]

Debugging Cyber-Physical System models is often challenging, as it requires identifying a potentially long, complex and heterogenous combination of events that resulted in a violation of the expected behavior of the system. In this paper we present CPSDebug, a tool for supporting designers in the debugging of failures in MAT- LAB Simulink/Stateflow models. CPSDebug implements a gray-box approach that combines testing, specification mining, and failure analysis to identify the causes of failures and explain their propagation in time and space. The evaluation of the tool, based on multiple usage scenarios and faults and direct feedback from engineers, shows that CPSDebug can effectively aid engineers during debugging tasks. [less ▲]

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See detailTowards Generalization of 3D Human Pose Estimation In The Wild
Baptista, Renato UL; Saint, Alexandre Fabian A UL; Al Ismaeil, Kassem UL et al

in International Conference on Pattern Recognition (ICPR) Workshop on 3D Human Understanding, Milan 10-15 January 2021 (2020)

In this paper, we propose 3DBodyTex.Pose, a dataset that addresses the task of 3D human pose estimation in-the-wild. Generalization to in-the-wild images remains limited due to the lack of adequate ... [more ▼]

In this paper, we propose 3DBodyTex.Pose, a dataset that addresses the task of 3D human pose estimation in-the-wild. Generalization to in-the-wild images remains limited due to the lack of adequate datasets. Existent ones are usually collected in indoor controlled environments where motion capture systems are used to obtain the 3D ground-truth annotations of humans. 3DBodyTex.Pose offers high quality and rich data containing 405 different real subjects in various clothing and poses, and 81k image samples with ground-truth 2D and 3D pose annotations. These images are generated from 200 viewpoints among which 70 challenging extreme viewpoints. This data was created starting from high resolution textured 3D body scans and by incorporating various realistic backgrounds. Retraining a state-of-the-art 3D pose estimation approach using data augmented with 3DBodyTex.Pose showed promising improvement in the overall performance, and a sensible decrease in the per joint position error when testing on challenging viewpoints. The 3DBodyTex.Pose is expected to offer the research community with new possibilities for generalizing 3D pose estimation from monocular in-the-wild images. [less ▲]

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See detailMeeting Designers Where They Are: Using Industry Events as a Research Venue for HCI and Design Methods Development
Lockton, Dan; Lallemand, Carine UL

Scientific Conference (2020)

There is much work in the CHI community about the ‘industry-academia divide’, and how to bridge it. One key crossover between HCI/UX scientists and practitioners is the development and use of tools and ... [more ▼]

There is much work in the CHI community about the ‘industry-academia divide’, and how to bridge it. One key crossover between HCI/UX scientists and practitioners is the development and use of tools and methods—boundary objects between academia and practice. Among other forms of collaboration, there is an underdeveloped opportunity for academics to make use of industry events (conferences, meetups, design jams) as a research venue in the context of tool and method development. This paper describes three cases from work in academia-industry engagement over the last decade, in which workshops or experiments have been run at industry events as a way of trialling and developing tools directly with practitioners. We discuss advantages of this approach and extract key insights and practical implications, highlighting how the CHI community might use this method more widely, gathering relevant research outcomes while contributing to knowledge exchange between academia and practice. [less ▲]

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See detailApproximation-Refinement Testing of Compute-Intensive Cyber-Physical Models: An Approach Based on System Identification
Menghi, Claudio UL; Nejati, Shiva UL; Briand, Lionel UL et al

in Proceedings of the 42nd International Conference on Software Engineering (2020)

Black-box testing has been extensively applied to test models of Cyber-Physical systems (CPS) since these models are not often amenable to static and symbolic testing and verification. Black-box testing ... [more ▼]

Black-box testing has been extensively applied to test models of Cyber-Physical systems (CPS) since these models are not often amenable to static and symbolic testing and verification. Black-box testing, however, requires to execute the model under test for a large number of candidate test inputs. This poses a challenge for a large and practically-important category of CPS models, known as compute-intensive CPS (CI-CPS) models, where a single simulation may take hours to complete. We propose a novel approach, namely ARIsTEO, to enable effective and efficient testing of CI-CPS models. Our approach embeds black-box testing into an iterative approximation-refinement loop. At the start, some sampled inputs and outputs of the CI-CPS model under test are used to generate a surrogate model that is faster to execute and can be subjected to black-box testing. Any failure-revealing test identified for the surrogate model is checked on the original model. If spurious, the test results are used to refine the surrogate model to be tested again. Otherwise, the test reveals a valid failure. We evaluated ARIsTEO by comparing it with S-Taliro, an open-source and industry-strength tool for testing CPS models. Our results, obtained based on five publicly-available CPS models, show that, on average, ARIsTEO is able to find 24% more requirements violations than S-Taliro and is 31% faster than S-Taliro in finding those violations. We further assessed the effectiveness and efficiency of ARIsTEO on a large industrial case study from the satellite domain. In contrast to S-Taliro, ARIsTEO successfully tested two different versions of this model and could identify three requirements violations, requiring four hours, on average, for each violation. [less ▲]

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See detailA Principle-Based Analysis of Weakly Admissible Semantics
Dauphin, Jérémie UL; Rienstra, Tjitze; van der Torre, Leon UL

in Computational Models of Argument - Proceedings of COMMA 2020, Perugia Italy, September 4-11, 2020 (2020)

Baumann, Brewka and Ulbricht recently introduced weak admissibility as an alternative to Dung’s notion of admissibility, and they use it to define weakly preferred, weakly complete and weakly grounded ... [more ▼]

Baumann, Brewka and Ulbricht recently introduced weak admissibility as an alternative to Dung’s notion of admissibility, and they use it to define weakly preferred, weakly complete and weakly grounded semantics of argumentation frameworks. In this paper we analyze their new semantics with respect to the principles discussed in the literature on abstract argumentation. Moreover, we introduce two variants of their new semantics, which we call qualified and semiqualified semantics, and we check which principles they satisfy as well. Since the existing principles do not distinguish our new semantics from the ones of Baumann et al., we also introduce some new principles to distinguish them. Besides selecting a semantics for an application, or for algorithmic design, our new principle-based analysis can also be used for the further search for weak admissibility semantics. [less ▲]

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See detailIntrusion detection on robot cameras using spatio-temporal autoencoders: A self-driving car application
Amrouche, Faouzi UL; Lagraa, Sofiane UL; Frank, Raphaël UL et al

in 91st IEEE Vehicular Technology Conference, VTC Spring 2020, Antwerp, Belgium, May 25-28, 2020 (2020)

Robot Operating System (ROS) is becoming more and more important and is used widely by developers and researchers in various domains. One of the most important fields where it is being used is the self ... [more ▼]

Robot Operating System (ROS) is becoming more and more important and is used widely by developers and researchers in various domains. One of the most important fields where it is being used is the self-driving cars industry. However, this framework is far from being totally secure, and the existing security breaches do not have robust solutions. In this paper we focus on the camera vulnerabilities, as it is often the most important source for the environment discovery and the decision-making process. We propose an unsupervised anomaly detection tool for detecting suspicious frames incoming from camera flows. Our solution is based on spatio-temporal autoencoders used to truthfully reconstruct the camera frames and detect abnormal ones by measuring the difference with the input. We test our approach on a real-word dataset, i.e. flows coming from embedded cameras of self-driving cars. Our solution outperforms the existing works on different scenarios. [less ▲]

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See detailShort Paper: An Update on Marked Mix-Nets: An Attack, a Fix and PQ Possibilities
Haines, Thomas; Pereira, Olivier; Roenne, Peter UL

in Financial Cryptography and Data Security - FC 2020 International Workshops, AsiaUSEC, CoDeFi, VOTING, and WTSC, Kota Kinabalu, Malaysia February 14, 2020, Revised Selected Papers (2020)

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See detailOptimizing the Performance of an Unpredictable UAV Swarm for Intruder Detection
Stolfi Rosso, Daniel UL; Brust, Matthias R. UL; Danoy, Grégoire UL et al

in Optimization and Learning - Third International Conference, OLA 2020, Cádiz, Spain, February 17-19, 2020, Proceedings (2020)

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See detailExamining the Relation Among Subjective Age and Working Memory in Old Age on a High-Frequency Basis Across 7 Days
Lücke, Anna; Siebert, Jelena; Schilling, Oliver et al

in Innovation in Aging (2020), 4(Supplement_1), 598-598

While increasing longitudinal evidence suggests that negative age views accelerate cognitive decline and increase dementia risk, we know little about such co-variance dynamics on a daily basis. We make ... [more ▼]

While increasing longitudinal evidence suggests that negative age views accelerate cognitive decline and increase dementia risk, we know little about such co-variance dynamics on a daily basis. We make use of subjective age and working memory performance data obtained six times a day over seven consecutive days as people went about their daily routines from 123 young-old (aged 66-69 years, 47.2% women) and 42 old-old (aged 86-90 years, 55.8% women) adults. Notably, multilevel models revealed considerably-sized short-term intra-individual variation of subjective age and working memory within days and these short-term within-day fluctuations in subjective age and working memory were coupled as expected. Hence, increased subjective age went along with lowered working memory confirming previous research. However, the respective between-day associations appeared reversed. Given this evidence of correlated short-term variability, we also discuss implications of different change dynamics that might explain moment-to-moment versus day-to-day associations between subjective age and working memory. [less ▲]

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See detailMachine Learning to Geographically Enrich Understudied Sources: A Conceptual Approach
Viola, Lorella UL; Verheul, Jaap

in Rocha, Ana; Steels, Luc; van den Herik, Jaap (Eds.) Proceedings of the 12th International Conference on Agents and Artificial Intelligence - Volume 1: ARTIDIGH (2020)

This paper discusses the added value of applying machine learning (ML) to contextually enrich digital collections. In this study, we employed ML as a method to geographically enrich historical datasets ... [more ▼]

This paper discusses the added value of applying machine learning (ML) to contextually enrich digital collections. In this study, we employed ML as a method to geographically enrich historical datasets. Specifically, we used a sequence tagging tool (Riedl and Padó 2018) which implements TensorFlow to perform NER on a corpus of historical immigrant newspapers. Afterwards, the entities were extracted and geocoded. The aim was to prepare large quantities of unstructured data for a conceptual historical analysis of geographical references. The intention was to develop a method that would assist researchers working in spatial humanities, a recently emerged interdisciplinary field focused on geographic and conceptual space. Here we describe the ML methodology and the geocoding phase of the project, focussing on the advantages and challenges of this approach, particularly for humanities scholars. We also argue that, by choosing to use largely neglected sources such as immigrant newspapers (a lso known as ethnic newspapers), this study contributes to the debate about diversity representation and archival biases in digital practices. [less ▲]

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See detailPrevalence of memory impairment 2000-2015 in Sao Paolo, Brazil
Ribeiro, Fabiana UL; de Oliveira Duarte, Yeda; Santos, Jair Licio Ferreira et al

in Alzheimer's and Dementia: the Journal of the Alzheimer's Association (2020), 16

Background: Decreases in prevalence of memory impairment and dementia over the last two decades have been observed in different countries for cohorts entering older age. We sought to explore the changes ... [more ▼]

Background: Decreases in prevalence of memory impairment and dementia over the last two decades have been observed in different countries for cohorts entering older age. We sought to explore the changes in prevalence of cognitive impairment across four waves of the Health, Welfare and Aging survey (SABE) with data collected in Sao Paolo, Brazil, in 2000, 2006, 2010, and 2015. Method: Mini Mental State Exam (MMSE) scores and covariate values were available for 5,191 respondents (62.4% female) aged 60 to 99 across four waves. Cognitive impairment was defined as having <=12 points on a 19-point abbreviated version of the MMSE. Age group, educational attainment (no formal schooling, primary, secondary, post-secondary), self-reported heart disease, stroke, diabetes, hypertension, and BMI (<18.5, 18.5-24.9, 25-29.9, 30+) were adjusted for. Result: In more recent waves, prevalence of cognitive impairment was higher for respondents aged 60-64 years (9.0% in 2015 vs. 4.6% in 2000), 65-69 years (9.7% in 2015 vs. 5.8% in 2006) and 70-74 years (13.9% in 2015 vs. 5.8% in 2006). Between 2015 and 2000, respondents were increasingly more likely to report some formal education (90.8% vs. 75.3%), secondary (17.6% vs. 7.3%) or postsecondary education (11.4% vs. 4.3%). Respondents were increasingly more likely to report hypertension (66.5% vs. 54.2%), diabetes (28.7% vs. 17.8%), and be overweight/obese (74.1% vs. 58.9%). In age-adjusted logistic regressions, respondents in 2015 were more likely to show cognitive impairment compared to 2000 (OR 1.84, CI 1.20-2.82). Conclusion: SABE respondents showed higher prevalence of cognitive impairment in 2015 compared to respondents of the same age in earlier waves, but differences disappeared after adjusting for chronic disease burden and educational attainment. [less ▲]

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See detailCompetitive Evolution of a UAV Swarm for Improving Intruder Detection Rates
Stolfi Rosso, Daniel UL; Brust, Matthias R. UL; Danoy, Grégoire UL et al

in 2020 IEEE International Parallel and Distributed Processing Symposium Workshops, IPDPSW 2020, New Orleans, LA, USA, May 18-22, 2020 (2020)

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See detailVote Selling Resistant Voting
Boyd, Colin; Haines, Thomas; Roenne, Peter UL

in Financial Cryptography and Data Security - FC 2020 International Workshops, AsiaUSEC, CoDeFi, VOTING, and WTSC, Kota Kinabalu, Malaysia February 14, 2020, Revised Selected Papers (2020)

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See detailDesigning different features of an interactive tabletop application to support collaborative problem-solving
Afkari, Hoorieh; Maquil, Valérie; Arend, Béatrice UL et al

Poster (2020)

The design space of tangible and multi-touch tabletop interfaces is complex, and little is known about how the different characteristics of tangible and multi-touch interactive features affect collabora ... [more ▼]

The design space of tangible and multi-touch tabletop interfaces is complex, and little is known about how the different characteristics of tangible and multi-touch interactive features affect collabora- tion strategies. With this work, we report on five different features designed for an interactive tabletop application to support collabo- rative problem-solving. We present the design details and describe preliminary results obtained from a user study with 15 participants. [less ▲]

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See detailProcess mining-based approach for investigating malicious login events
Lagraa, Sofiane UL; State, Radu UL

in IEEE/IFIP Network Operations and Management Symposium, Budapest, Hungary, April 20-24, 2020 (2020)

A large body of research has been accomplished on prevention and detection of malicious events, attacks, threats, or botnets. However, there is a lack of automatic and sophisticated methods for ... [more ▼]

A large body of research has been accomplished on prevention and detection of malicious events, attacks, threats, or botnets. However, there is a lack of automatic and sophisticated methods for investigating malicious events/users, understanding the root cause of attacks, and discovering what is really hap- pening before an attack. In this paper, we propose an attack model discovery approach for investigating and mining malicious authentication events across user accounts. The approach is based on process mining techniques on event logs reaching attacks in order to extract the behavior of malicious users. The evaluation is performed on a publicly large dataset, where we extract models of the behavior of malicious users via authentication events. The results are useful for security experts in order to improve defense tools by making them robust and develop attack simulations. [less ▲]

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See detailA Look into Privacy-Preserving Blockchains
Khan, Nida UL; Nassar, Mohamed

in IEEE BCA @AICCSA 2019 - Workshop on Blockchain and it's Applications (2020)

Blockchain is a revolutionary technology promising a new generation of decentralized, transparent and tamper-proof database systems. However, one of the main challenges of the emerging blockchain systems ... [more ▼]

Blockchain is a revolutionary technology promising a new generation of decentralized, transparent and tamper-proof database systems. However, one of the main challenges of the emerging blockchain systems remains to address data privacy. While in Bitcoin and similar e-cash systems, privacy was limited to anonymity and addressed by using cryptographic pseudonyms for identification and authentication of parties, the question of privacy has more breadth in systems maintaining actual data such as medical records or energy meters. In this paper, we look into recently proposed privacy-preserving blockchains, analyze their strengths and weaknesses, and highlight research questions requiring future investigation. We conclude that privacy-preserving blockchains are still in their infancy and more research is definitely needed in this area. [less ▲]

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See detailDealing with Non-Uniform Demands in Flexible GEO Satellites: The Carrier Aggregation Perspective
Lagunas, Eva UL; Kibria, Mirza; Al-Hraishawi, Hayder UL et al

in 10th Advanced Satellite Multimedia Systems Conference (ASMS) and 16th Signal Processing for Space Communications Workshop (SPSC), October 2020. (2020)

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See detailA Cooperative Coevolutionary Approach to Maximise Surveillance Coverage of UAV Swarms
Stolfi Rosso, Daniel UL; Brust, Matthias R. UL; Danoy, Grégoire UL et al

in IEEE 17th Annual Consumer Communications & Networking Conference CCNC 2020, Las Vegas, NV, USA, January 10-13, 2020 (2020)

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See detailA Worst-Case Performance Optimization Based Design Approach to Robust Symbol-Level Precoding for Downlink MU-MIMO
Haqiqatnejad, Alireza UL; Shahbazpanahi, Shahram UL; Ottersten, Björn UL

in IEEE Global Conference on Signal and Information Processing (GlobalSIP), Ottawa 11-14 November 2019 (2020)

This paper addresses the optimization problem of symbol-level precoding (SLP) in the downlink of a multiuser multiple-input multiple-output (MU-MIMO) wireless system while the precoder's output is subject ... [more ▼]

This paper addresses the optimization problem of symbol-level precoding (SLP) in the downlink of a multiuser multiple-input multiple-output (MU-MIMO) wireless system while the precoder's output is subject to partially-known distortions. In particular, we assume a linear distortion model with bounded additive noise. The original signal-to-interference- plus-noise ratio (SINR) -constrained SLP problem minimizing the total transmit power is first reformulated as a penalized unconstrained problem, which is referred to as the relaxed robust formulation. We then adopt a worst-case design approach to protect the users' intended symbols and the targeted constructive interference with a desired level of confidence. Due to the non-convexity of the relaxed robust formulation, we propose an iterative algorithm based on the block coordinate ascent-descent method. We show through simulation results that the proposed robust design is flexible in the sense that the CI constraints can be relaxed so as to keep a desirable balance between achievable rate and power consumption. Remarkably, the new formulation yields more energy-efficient solutions for appropriate choices of the relaxation parameter, compared to the original problem. [less ▲]

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See detailA Dynamics-based Approach for the Target Control of Boolean Networks
Su, Cui; Pang, Jun UL

in Proceedings of the 11th ACM International Conference on Bioinformatics, Computational Biology and Health Informatics (2020)

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See detailVisualisierungen des Induktionsprinzips
Perucca, Antonella UL; Todorovic, Milko

in Beiträge zum Mathematikunterricht 2020 (2020)

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See detailAuthentication and Key Management Automation in Decentralized Secure Email and Messaging via Low-Entropy Secrets
Vazquez Sandoval, Itzel UL; Atashpendar, Arash; Lenzini, Gabriele UL

in Proceedings of the 17th International Joint Conference on e-Business and Telecommunications (2020)

We revisit the problem of entity authentication in decentralized end-to-end encrypted email and secure messaging to propose a practical and self-sustaining cryptographic solution based on password ... [more ▼]

We revisit the problem of entity authentication in decentralized end-to-end encrypted email and secure messaging to propose a practical and self-sustaining cryptographic solution based on password-authenticated key exchange (PAKE). This not only allows users to authenticate each other via shared low-entropy secrets, e.g., memorable words, without a public key infrastructure or a trusted third party, but it also paves the way for automation and a series of cryptographic enhancements; improves security by minimizing the impact of human error and potentially improves usability. First, we study a few vulnerabilities in voice-based out-of-band authentication, in particular a combinatorial attack against lazy users, which we analyze in the context of a secure email solution. Next, we propose solving the problem of secure equality test using PAKE to achieve entity authentication and to establish a shared high-entropy secret key. Our solution lends itself to offline settings, compatible with the inherently asynchronous nature of email and modern messaging systems. The suggested approach enables enhancements in key management such as automated key renewal and future key pair authentications, multi-device synchronization, secure secret storage and retrieval, and the possibility of post-quantum security as well as facilitating forward secrecy and deniability in a primarily symmetric-key setting. We also discuss the use of auditable PAKEs for mitigating a class of online guess and abort attacks in authentication protocols. [less ▲]

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See detailNGAP: a novel hybrid metaheuristic algorithm for round-trip carsharing fleet planning
Changaival, Boonyarit UL; Danoy, Grégoire UL; Kliazovich et al

in GECCO '20: Genetic and Evolutionary Computation Conference, Companion Volume, Cancún, Mexico, July 8-12, 2020 (2020)

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See detailLarge Intelligent Surface for Positioning in Millimeter Wave MIMO Systems
He, Jiguang; Wymeersch, Henk; Kong, Long UL et al

in 2020 IEEE 91st Vehicular Technology Conference (VTC2020-Spring) (2020)

Millimeter-wave (mmWave) multiple-input multiple-output (MIMO) system for the fifth generation (5G) cellular communications can also enable single-anchor positioning and object tracking due to its large ... [more ▼]

Millimeter-wave (mmWave) multiple-input multiple-output (MIMO) system for the fifth generation (5G) cellular communications can also enable single-anchor positioning and object tracking due to its large bandwidth and inherently high angular resolution. In this paper, we introduce the newly invented concept, large intelligent surface (LIS), to mmWave positioning systems, study the theoretical performance bounds (i.e., Cramér-Rao lower bounds) for positioning, and evaluate the impact of the number of LIS elements and the value of phase shifters on the position estimation accuracy compared to the conventional scheme with one direct link and one non-line-of-sight path. It is verified that better performance can be achieved with a LIS from the theoretical analyses and numerical study. [less ▲]

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See detailCommit-Aware Mutation Testing
Ma, Wei UL; Laurent, Thomas; Ojdanić, Miloš UL et al

in IEEE International Conference on Software Maintenance and Evolution (ICSME) (2020)

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See detailAutomatic Testing and Improvement of Machine Translation
Sun, Zeyu; Zhang, Jie; Harman, Mark et al

in International Conference on Software Engineering (ICSE) (2020)

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See detailMeasures of Executive Functions and Mathematical Skills are Distinct Even at a Young Age: A Meta-Analysis with Preschool Children
Emslander, Valentin UL; Scherer, Ronny

Scientific Conference (2020)

Measures of executive functions (inhibition, attention shifting, working memory) are linked to measures of mathematical skills in school students and adults. However, the magnitude of this relation in ... [more ▼]

Measures of executive functions (inhibition, attention shifting, working memory) are linked to measures of mathematical skills in school students and adults. However, the magnitude of this relation in preschool children is unclear. Following the literature on the differentiation of cognitive skills over time, some researchers suggest that tests of executive functions and mathematical skills measure the same underlying construct, while others suggest that they measure correlated but distinct constructs. This dispute does not only tap the question of how the constructs can be understood but also the question of cost and test efficiency (i.e., assessments of single vs. multiple constructs). Clarifying the relation between measures of the two constructs can be especially challenging because preschoolers cannot fill in commonly used questionnaires that require them to read. Thus, researchers have to resort to behavioral, verbal, apparatus-, or computer-based assessments of executive functions. As a result, executive functions may vary in their relation to mathematical skills as a consequence of their measurement. We examined the link between executive functions and early mathematical skills measures, conducting a meta-analysis of 26 studies containing 238 effect sizes for a total sample of 24,256 preschool children. Specifically, we synthesized the corresponding correlations and aimed to clarify which executive function assessments were used for preschool children and how assessment characteristics may moderate the correlation between executive functions and mathematical skills. Three-level random-effects meta-analysis revealed a small to moderate average correlation between executive functions and mathematical skills measures of preschool children, r = 0.35. The type of assessment (behavioral, verbal, apparatus-, or computer-based assessments) did not moderate this relation. Investigating the three executive functions separately, we found average correlations of r = 0.31 between mathematical skills and inhibition, r = 0.38 between mathematical skills and attention shifting, and r = 0.36 between mathematical skills and updating. These analyses will be supplemented by further moderator and sensitivity analyses. These findings emphasize the significant link between executive functions and mathematical skills measures in preschoolers—hereby, supporting that the measures of both constructs are distinct. In addition, under-researched areas around the assessment of executive functions and mathematical abilities will be discussed. [less ▲]

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See detailComputational Metabolomics: From Cheminformatics to Machine Learning (Dagstuhl Seminar 20051)
Böcker, Sebastian; Broeckling, Corey; Schymanski, Emma UL et al

in Dagstuhl Reports (2020)

Dagstuhl Seminar 20051 on Computational Metabolomics is the third edition of seminars onthis topic and focused on Cheminformatics and Machine Learning. With the advent of higherprecision instrumentation ... [more ▼]

Dagstuhl Seminar 20051 on Computational Metabolomics is the third edition of seminars onthis topic and focused on Cheminformatics and Machine Learning. With the advent of higherprecision instrumentation, application of metabolomics to a wider variety of small molecules, andever increasing amounts of raw and processed data available, developments in cheminformaticsand machine learning are sorely needed to facilitate interoperability and leverage further insightsfrom these data. Following on from Seminars 17491 and 15492, this edition convened bothexperimental and computational experts, many of whom had attended the previous sessions andbrought much-valued perspective to the week’s proceedings and discussions. Throughout theweek, participants first debated on what topics to discuss in detail, before dispersing into smaller,focused working groups for more in-depth discussions. This dynamic format was found to bemost productive and ensured active engagement amongst the participants. The abstracts inthis report reflect these working group discussions, in addition to summarising several informalevening sessions. Action points to follow-up on after the seminar were also discussed, includingfuture workshops and possibly another Dagstuhl seminar in late 2021 or 2022. [less ▲]

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See detailMuteria: An Extensible and Flexible Multi-Criteria Software Testing Framework
Titcheu Chekam, Thierry UL; Papadakis, Mike UL; Le Traon, Yves UL

in ACM/IEEE International Conference on Automation of Software Test (AST) 2020 (2020)

Program based test adequacy criteria (TAC), such as statement, branch coverage and mutation give objectives for software testing. Many techniques and tools have been developed to improve each phase of the ... [more ▼]

Program based test adequacy criteria (TAC), such as statement, branch coverage and mutation give objectives for software testing. Many techniques and tools have been developed to improve each phase of the TAC-based software testing process. Nonetheless, The engineering effort required to integrate these tools and techniques into the software testing process limits their use and creates an overhead to the users. Especially for system testing with languages like C, where test cases are not always well structured in a framework. In response to these challenges, this paper presents Muteria, a TAC-based software testing framework. Muteria enables the integration of multiple software testing tools. Muteria abstracts each phase of the TAC-based software testing process to provide tool drivers interfaces for the implementation of tool drivers. Tool drivers enable Muteria to call the corresponding tools during the testing process. An initial set of drivers for KLEE, Shadow and SEMu test-generation tools, Gcov, and coverage.py code coverage tools, and Mart mutant generation tool for C and Python programming language were implemented with an average of 345 lines of Python code. Moreover, the user configuration file required to measure code coverage and mutation score on a sample C programs, using the Muteria framework, consists of less than 15 configuration variables. Users of the Muteria framework select, in a configuration file, the tools and TACs to measure. The Muteria framework uses the user configuration to run the testing process and report the outcome. Users interact with Muteria through its Application Programming Interface and Command Line Interface. Muteria can benefit to researchers as a laboratory to execute experiments, and to software practitioners. [less ▲]

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See detailSoK: Techniques for Verifiable Mix Nets
Mueller, Johannes UL

in Haines, Thomas; Mueller, Johannes (Eds.) IEEE Computer Security Foundations Symposium (2020)

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See detailFlipping Geometric Triangulations on Hyperbolic Surfaces
Despré, vincent; Schlenker, Jean-Marc UL; Teillaud, Monique

in symposium on computational geometry (SoCG) (2020)

We consider geometric triangulations of surfaces, i.e., triangulations whose edges can be realized by disjoint locally geodesic segments. We prove that the flip graph of geometric triangulations with ... [more ▼]

We consider geometric triangulations of surfaces, i.e., triangulations whose edges can be realized by disjoint locally geodesic segments. We prove that the flip graph of geometric triangulations with fixed vertices of a flat torus or a closed hyperbolic surface is connected. We give upper bounds on the number of edge flips that are necessary to transform any geometric triangulation on such a surface into a Delaunay triangulation. [less ▲]

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See detailReceive Beamforming for Ultrareliable Random Access based SWIPT
Kisseleff, Steven UL; Chatzinotas, Symeon UL; Ottersten, Björn UL

in Proceedings of IEEE 31st Annual International Symposium on Personal, Indoor and Mobile Radio Communications (2020)

Ultrareliable uplink communication based on random access poses novel research challenges for the receiver design. Here, the uncertainty imposed by the random access and a large amount of interfering ... [more ▼]

Ultrareliable uplink communication based on random access poses novel research challenges for the receiver design. Here, the uncertainty imposed by the random access and a large amount of interfering transmissions is the limiting factor for the system performance. Recently, this type of communication has been addressed in context of simultaneous wireless information and power transfer (SWIPT). The need to adapt the power splitting to the signal states according to the underlying random access has been tackled by introducing a predictor, which determines the valid states of the received signal based on the long-term observation. Hence, the power splitting factor is scaled accordingly in order to guarantee ultrareliable communication and maximized harvested energy.In this work, we extend the considered SWIPT scenario by introducing multiple antennas at the receiver side. Through this, the received energy can be substantially increased, if the energy harvesting parameters and the spatial filter coefficients are jointly optimized. Hence, we propose an optimization procedure, which aims at maximizing the harvested energy under the ultrareliability constraint. The mentioned prediction method is then combined with the optimization solution and the resulting system performance is numerically evaluated. [less ▲]

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See detailA performance evaluation of weight-constrained conditioned portfolio optimization
Schiltz, Jang UL; Boissaux, Marc UL

Scientific Conference (2019, December 20)

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See detailFrom home to early childhood education: beliefs, language ideologies and OPOL
Kirsch, Claudine UL

Scientific Conference (2019, December 18)

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See detailHome literacy environment and family language policy of immigrant families in Luxembourg
Aleksic, Gabrijela UL; Bebic, Dzoen Dominique UL

Scientific Conference (2019, December 18)

Early literacy skills are critical for children’s later academic achievement. A wealth of research showed that children’s home languages should not be abandoned, as they are crucial for promoting dynamic ... [more ▼]

Early literacy skills are critical for children’s later academic achievement. A wealth of research showed that children’s home languages should not be abandoned, as they are crucial for promoting dynamic multilingualism, assuring cross-linguistic transfer and developing identities. To explore home literacy environment and family language policy of language minority preschool children in Luxembourg, we obtained 603 parent questionnaires, tested 226 children age 4 to 6 in their home languages and Luxembourgish, and interviewed 31 families. The results from the questionnaires showed that the home resources and parent involvement influenced children’s language awareness and their print knowledge irrespective of parent’s education and their wealth. Concerning children’s competences in Luxembourgish, children with positive attitudes towards their school did better than their peers in other schools. In the interviews, parents explained that maintaining home language is important for keeping connections with family, friends and their culture. This is the language parents feel emotionally connected to and the easiest to transmit to their children. Language maintenance is mostly achieved through conversations, movies, games and books in the home languages, children’s attendance of language schools on weekends, celebrations of traditions as well as holidays in the native country of the parents. The home language is, however, not something parents enforce too strictly, as they mostly correct the children’s linguistic mistakes by simple repetition. It is often with great pride that parents report their children having an excellent proficiency in their home language. Finally, through our professional development training in translanguaging we are helping teachers to integrate children’s different home languages and cultures into the classroom and strengthen the home-school collaboration in order to support children’s well-being, learning and identities. [less ▲]

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See detailA professional development course in translanguaging: Teachers’ stance, design, and shifts
Aleksic, Gabrijela UL

Scientific Conference (2019, December 14)

The school population in Luxembourg is highly socially, culturally, and linguistically diverse. The new law in 2017 has declared multilingual early education mandatory, with the focus not only on the ... [more ▼]

The school population in Luxembourg is highly socially, culturally, and linguistically diverse. The new law in 2017 has declared multilingual early education mandatory, with the focus not only on the development of Luxemburgish, but also familiarizing children with French and valuing their home languages. Thus, our project aims to: (1) offer a professional development (PD) course in translanguaging to preschool teachers, (2) involve children’s families to reinforce home-school collaboration, and (3) foster children’s cognitive, linguistic, and socio-emotional engagement in the classroom. With teachers, we use focus groups, questionnaires, and language portraits, with parents, we employ questionnaires and interviews, and with children, a test in early literacy and numeracy in school and home language and video observations. Translanguaging is the use of a full linguistic repertoire to make meaning (Otheguy, García, & Reid, 2015). Translanguaging pedagogy is the main topic of our 22 hour PD course (June – December 2019) for 40 teachers. In the focus groups, the teachers shared their negative translanguaging stance towards the use of children’s home languages in the classroom, convinced that it hindered the development of Luxembourgish. Teachers, however, in some instances incorporated a translanguaging design (e.g. multilingual stories, morning greetings) and translanguaging shift (e.g. translations by older children). The project addresses these negative translanguaging stances through practical activities and a close collaboration with parents, children and organisational stakeholders. The preliminary results from parent questionnaires and tests with children will provide a bigger picture of the effect of translanguaging pedagogy from our PD course on all the actors involved. References Otheguy, R., García, O., & Reid, W. (2015). Clarifying translanguaging and deconstructing named languages: A perspective from linguistics. Applied Linguistic Review, 6(3), 281–307. [less ▲]

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See detailLocalization Performance of 1-Bit Passive Radars in NB-IoT Applications
Sedighi, Saeid UL; Mishra, Kumar Vijay; Shankar, Bhavani UL et al

in Sedighi, Saeid; Mishra, Kumar Vijay; Shankar, Bhavani (Eds.) et al Localization Performance of 1-Bit Passive Radars in NB-IoT Applications (2019, December 14)

Location-based services form an important use-case in emerging narrowband Internet-of-Things (NB-IoT) networks. Critical to this offering is an accurate estimation of the location without overlaying the ... [more ▼]

Location-based services form an important use-case in emerging narrowband Internet-of-Things (NB-IoT) networks. Critical to this offering is an accurate estimation of the location without overlaying the network with additional active sensors. The massive number of devices, low power requirement, and low bandwidths restrict the sampling rates of NB-IoT receivers. In this paper, we propose a novel low-complexity approach for NB-IoT target delay estimation in cases where one-bit analog-to-digital-converters (ADCs) are employed to sample the received radar signal instead of high-resolution ADCs. This problem has potential applications in the design of inexpensive NB-IoT radar and sensing devices. We formulate the target estimation as a multivariate fractional optimization problem and solve it via Lasserre's semi-definite program relaxation. Numerical experiments suggest feasibility of the proposed approach yielding high localization accuracy with a very low number of 1-bit samples. [less ▲]

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See detailYoung emergent multilingual children's agency in learning new language in trilingual Luxembourg
Mortini, Simone UL

Scientific Conference (2019, December 14)

Studies on translanguaging suggest that opportunities to use languages flexibly in the classroom may give children some agency over their language use and facilitate their language learning (García ... [more ▼]

Studies on translanguaging suggest that opportunities to use languages flexibly in the classroom may give children some agency over their language use and facilitate their language learning (García & Kleifgen, 2010). In the emerging field of preschool bilingual education, scholars investigate the concept of child agency in relation to the learning of multiple languages (Schwartz, 2018). Children were shown to actively and creatively contribute to their language learning through choosing to interact in a particular language. Studies on young children’s translanguaging and agency nevertheless remain scarce, especially in multilingual contexts involving more than two languages (Schwartz et al., forthcoming). The present study focuses on eight children’s agentive behaviour in multilingual practices in two formal and two non-formal early childhood education institutions participating in a larger longitudinal research project on the development of multilingual pedagogies in trilingual Luxembourg. I drew on multidimensional qualitative research methods, including 65 days of participant observations, fieldnotes, video-recordings and semi-structured interviews with the practitioners. The findings show that all the children made use of various non-linguistic strategies and at least four named languages and translanguaged for various purposes (e.g. demonstrating knowledge, meaning making). Moreover, they showed two types of agentive behaviour: ‘participatory agency’ (e.g. adapting learning to practitioners’ requirements) and ‘controlling agency’ (e.g. influencing or changing peers’ or practitioners’ language use). The findings should deepen our understanding of the interplay between agency and translanguaging. García, O., & Kleifgen, J. (2010). Educating Emergent Bilinguals. Policies, Programs and Practices for English Language Learners. New York: Teachers College Press. Schwartz, M. (2018). Preschool Bilingual Education: Agency in Interactions between Children, Teachers, and Parents. Dordrecht: Springer. Schwartz, M., Kirsch, C., & Mortini, S. (forthcoming). Young children’s language-based agency in multilingual contexts in Luxembourg and Israel. (Applied Linguistic Review). Manuscript accepted for publication. [less ▲]

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See detailWhy is the Market Skewness-Return Relationship Negative?
Lehnert, Thorsten UL

Scientific Conference (2019, December 13)

The observed negative relationship between market skewness and excess return or the negative price of market skewness risk in the cross-section of stock returns is somewhat counterintuitive when we ... [more ▼]

The observed negative relationship between market skewness and excess return or the negative price of market skewness risk in the cross-section of stock returns is somewhat counterintuitive when we consider the usual interpretation of e.g. option-implied skewness as an indicator of jump risk or downside risk. One possible explanation for this inconsistency is that there are factors affecting option-implied market skewness other than jump risk in the stock market. In this paper, I find that price pressure associated with “crowded trades” of mutual funds is an important endogenous factor. Given that retail investors are prone to herding, the directional trading of mutual funds is correlated, and their collective actions can generate short-term price pressure on aggregate stock prices. Short sellers systematically exploit these patterns not only in the equity lending market, but also in the options market. In line with this economic channel, I find that firstly, the significant negative relationship between market skewness and returns becomes insignificant, once I control for price pressure. Secondly, the negative relationship is only present for the “bad” downside component of risk-neutral skewness, associated with out-of-the-money put options. For the “good” upside component of risk-neutral skewness, associated with out-of-the-money call options, the relationship is always positive. Thirdly, price pressure affects the skewness-return relationship, which can be clearly distinguished from the impact of flows on the volatility-return relationship in terms of the leverage effect. [less ▲]

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See detailConsolidating Observation of Land and Sea Level Changes around South Georgia Island
Teferle, Felix Norman UL; Hunegnaw, Addisu UL; Hibbert, Angela et al

Poster (2019, December 13)

With its mid-ocean location in the Southern Atlantic Ocean South Georgia Island is in a key position for the oceanic and geodetic global monitoring networks. Since 2013 the tide gauge at King Edward Point ... [more ▼]

With its mid-ocean location in the Southern Atlantic Ocean South Georgia Island is in a key position for the oceanic and geodetic global monitoring networks. Since 2013 the tide gauge at King Edward Point (KEP) with GLOSS ID 187 has been monitored using a GNSS station nearby on Brown Mountain. By accurately geo-referencing the tide gauge and monitoring any vertical land movements, a continuous record of its datum within the Permanent Service for Mean Sea Level (PSMSL) can be established, which in turn makes the recorded and averaged sea levels useful for long-term studies and satellite altimetry calibrations. In 2014 another GNSS station was installed at KEP after local subsidence was sus-pected and later on three additional GNSS stations came to service at the periphery of the main island, making it possible to monitor uplift/subsidence wider afield. Further-more, together with four precise levelling campaigns of the KEP benchmark network in 2013, 2014 and two in 2017, it has also been possible to investigate the very local character of the vertical motions near KEP, i.e. the stability of the jetty upon which the tide gauge is mounted. In this study, we will present the results from the GNSS and precise levelling meas-urements, and will discuss their impact on the sea level record from the KEP tide gauge and nearby satellite altimetry sea surface heights. This study comes at a timely manner as during the Austral Summer 2019/2020 the jetty will be stabilized and en-larged, and consequently the current tide gauge will be replaced by a new one. Our measurements show that uplift is observed all over South Georgia Island while the ar-ea at KEP and particularly the jetty with tide gauge are subsiding relative to the rest of the island. In contrast, results for the tide gauge record show a lower magnitude of ob-served sea level rise than expected from nearby satellite altimetry. We will revisit all geodetic and oceanic observations in an attempt to improve the agreement between these measurements to summarize the status before the work at the jetty begins. [less ▲]

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See detailUsing the Vertical Land Movement estimates from the IGS TIGA combined solution to derive Global Mean Sea Level changes
Bogusz, Janusz; Hunegnaw, Addisu UL; Teferle, Felix Norman UL et al

Scientific Conference (2019, December 13)

Global mean sea level (GMSL) is now widely recognized to have risen between 1 to 2 mm/yr depending on location since the 20th century. Prior to the satellite altimetry era, GMSL was primarily estimated ... [more ▼]

Global mean sea level (GMSL) is now widely recognized to have risen between 1 to 2 mm/yr depending on location since the 20th century. Prior to the satellite altimetry era, GMSL was primarily estimated from a set of secular tide gauge records relative to coastal benchmarks. Recent measurements of GPS (Global Positioning System) have been demonstrated as a useful tool of a direct estimate of Vertical Land Motion (VLM) induced by both long and short-term geophysical and human-induced processes in a geocentric reference frame. This presentation will provide the results of a combination performed using the CATREF software of three independent GPS daily solutions provided by British Isles continuous GNSS Facility – University of Luxembourg consortium (BLT), German Research Centre for Geosciences (GFZ) and University of La Rochelle (ULR) under the auspices of the Tide Gauge Benchmark Monitoring (TIGA) Working Group (WG), that results in a spatially comprehensive map of VLM near or close to tide gauge benchmarks. The combination was performed in accordance with the second re-processing campaign (repro2) of the IGS (International GNSS Service). Long coastal tide gauge records from the archives maintained at the Permanent Service for Mean Sea Level (PSMSL) were extracted for relative sea level estimates. To cross-compare the sea level rates over the years, we employed observations between 1900-2016. Then, the time series were cut and analyzed separately, ceteris paribus, for the period 1960-2016. This analysis was aimed at a cross-comparison of relative sea level trends and their changes over the years. The stochastic part of the tide gauge records was analyzed with Maximum Likelihood Estimation (MLE) and assumed several different combinations of noise models with the Bayesian Information Criterion (BIC) providing a means to identify the preferred one. The relative sea level estimates were corrected by the inverted barometric effect to the tide-gauge records using data from the 20th century Reanalysis project version V2C, the effect of wind stress on the surface of the ocean in both, zonal and meridional components, as well as Pacific Decadal Oscillation (PDO) and the North Pacific Gyre Oscillation (NPGO) influencing Pacific tide gauge records. The GPS-based velocities were corrected by Glacial Isostatic Adjustment (GIA) effect using ICE-6G(VM5a) model with associated geoid rate and post seismic decays using ITRF2014 estimates. Also, environmental loading models were employed to account for present-day elastic loading in VLM. The Mean Sea Level (MSL) trends from tide gauges and VLM-corrected MSL trends using GIA model (TG+GIA) and the TIGA combination (TG+TIGA) were determined. Our final reconstruction of GMSL based on the MSL records from 1900 to 2016 where the VLM uncertainty is smaller than 0.7 mm/yr indicate a long-term trend of 1.75 +/- 0.2 mm/yr and is in good agreement with several similar determinations. [less ▲]

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See detailConventional EO Satellites vs. CubeSats; FDL - AI flood detection onboard a Nano Satellite
Backes, Dietmar UL; Schumann, Guy; Teferle, Felix Norman UL

Scientific Conference (2019, December 11)

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See detailTracking hurricanes Harvey and Irma using GPS tropospheric products
Ejigu, Yohannes Getachew; Teferle, Felix Norman UL; Hunegnaw, Addisu UL et al

Poster (2019, December 10)

The 2017 Hurricanes season was one of the most powerful severe weather events producing catastrophic socio-economic and environmental effects on the east coast of the United States. Therefore, tracking ... [more ▼]

The 2017 Hurricanes season was one of the most powerful severe weather events producing catastrophic socio-economic and environmental effects on the east coast of the United States. Therefore, tracking their path accurately is extremely useful. Today Global Navigation Satellite Systems (GNSS) tropospheric products, such as Zenith Wet Delays (ZWD), and Integrated Water Vapor (IWV) are used as complementary data sets in Numerical Weather Prediction (NWP) models. In this study, we employed GPS-derived IWV and horizontal tropospheric gradient information to monitor and investigate the complicated characteristics of hurricane events in their spatial and temporal distribution using a dense ground network of GPS stations. Our results show that a surge in GPS-derived IWV occurred several hours prior to the manifestation of the major hurricanes Harvey and Irma. We used the derived GPS-derived IWV information as input to spaghetti lines weather models, allowing us to predict the paths of Harvey and Irma hurricanes. As such, a parameter directly estimated from GPS can provide an additional resource for improving the monitoring of hurricane paths [less ▲]

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See detailCarrier Aggregation in Multi-Beam High Throughput Satellite Systems
Kibria, Mirza UL; Lagunas, Eva UL; Maturo, Nicola UL et al

in Carrier Aggregation in Multi-Beam High Throughput Satellite Systems (2019, December 10)

Carrier Aggregation (CA) is an integral part of current terrestrial networks. Its ability to enhance the peak data rate, to efficiently utilize the limited available spectrum resources and to satisfy the ... [more ▼]

Carrier Aggregation (CA) is an integral part of current terrestrial networks. Its ability to enhance the peak data rate, to efficiently utilize the limited available spectrum resources and to satisfy the demand for data-hungry applications has drawn large attention from different wireless network communities. Given the benefits of CA in the terrestrial wireless environment, it is of great interest to analyze and evaluate the potential impact of CA in the satellite domain. In this paper, we study CA in multi-beam high throughput satellite systems. We consider both inter-transponder and intra-transponder CA at the satellite payload level of the communication stack, and we address the problem of carrier-user assignment assuming that multiple users can be multiplexed in each carrier. The transmission parameters of different carriers are generated considering the transmission characteristics of carriers in different transponders. In particular, we propose a flexible carrier allocation approach for a CA enabled multi-beam satellite system targeting a proportionally fair user demand satisfaction. Simulation results and analysis shed some light on this rather unexplored scenario and demonstrate the feasibility of the CA in satellite communication systems. [less ▲]

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See detailHydrogeological effects on terrestrial gravity measurements
Van Camp, Michel; de Viron, Olivier; Dassargues, Alain et al

Scientific Conference (2019, December 10)

For the 20 last years, terrestrial and satellite gravity measurements have reached such a precision that they allow for identification of the signatures from water storage fluctuations. In particular ... [more ▼]

For the 20 last years, terrestrial and satellite gravity measurements have reached such a precision that they allow for identification of the signatures from water storage fluctuations. In particular, hydrogeological effects induce significant time-correlated signature in the gravity time series. Gravity response to rainfall is a complex function of the local geologic and climatic conditions, e.g., rock porosity, vegetation, evaporation, and runoff rates. The gravity signal combines contributions from many geophysical processes, source separation being a major challenge. At the local scale and short-term, the associated gravimetric signatures often exceed the tectonic and GIA effects, and monitoring gravity changes is a source of information on local groundwater mass balance, and contributes to model calibrations. Some aquifer main characteristics can then be inferred by combining continuous gravity, geophysical and hydrogeological measurements. In Membach, Belgium, a superconducting gravimeter has monitored gravity continuously for more than 24 years. This long time series, together with 300 repeated absolute gravity measurements and environmental monitoring, has provided valuable information on the instrumental, metrological, hydrogeological and geophysical points of view. This has allowed separating the signal sources and monitoring partial saturation dynamics in the unsaturated zone, convective precipitation and evapotranspiration at a scale of up to 1 km², for signals smaller than 1 nm/s², equivalent to 2.5 mm of water. Based on this experience, another superconducting gravimeter was installed in 2014 in the karst zone of Rochefort, Belgium. In a karst area, where the vadose zone is usually thicker than in other contexts, combining gravity measurements at the surface and inside accessible caves is a way to separate the contribution from the unsaturated zone lying between the two instruments, from the saturated zone underneath the cave, and the common mode effects from the atmosphere or other regional processes. Those experiments contribute to the assessment of the terrestrial hydrological cycle, which is a major challenge of the geosciences associated with key societal issues: availability of freshwater, mitigation of flood hazards, or measurement of evapotranspiration. [less ▲]

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See detailAbsolute Gravity and Uplift in the Yellowstone Caldera
van Dam, Tonie UL; Francis, Olivier UL

Scientific Conference (2019, December 10)

GPS time-series of uplift show that points in and around the caldera have gone through cycles of uplift, followed by subsidence since observations began about three decades ago. A dramatic increase in the ... [more ▼]

GPS time-series of uplift show that points in and around the caldera have gone through cycles of uplift, followed by subsidence since observations began about three decades ago. A dramatic increase in the uplift rate started in 2004 at the GPS station LKWY near Yellowstone Lake and Old Faithful, OFWY. Since 2010, the sites have subsided, began uplifting again in 2014 coincidentally after a M 4.8 earthquake near the Norris Geyser Basin, and then started subsiding again in 2016. The cause of the episodic uplift and subsidence and the spatial pattern of the surface displacement are not yet well understood. The 2003-2009 episode of rapid uplift is believed to result from deep source magma intrusion simultaneous with depressurization of the hydrothermal systems beneath the Norris Geyser Basin. But whether it is caused by the intrusion of magma from a distant reservoir, or by the expulsion and localized trapping of pressurized water and gas from rock that is already in-place, is not known. We have taken observations of absolute gravity at LKWY and OFWY almost annually since 2009. In this presentation, we compare gravity and uplift and provide some insight into the mechanism driving the uplift/subsidence cycles. [less ▲]

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See detailParameter identification problem in bimaterial human skin and sensitivity analysis : Uncertainties in biomechanics of skin
Sutula, Danas; Elouneg, Aflah; Sensale, Marco UL et al

Scientific Conference (2019, December 09)

The proposed paper concerns the prediction of the numerical response of a biomechanical structure submitted to an unknown external loading state. The methodology is based on homogeneous and then ... [more ▼]

The proposed paper concerns the prediction of the numerical response of a biomechanical structure submitted to an unknown external loading state. The methodology is based on homogeneous and then heterogeneous structures such as healthy or pathological cutaneous tissues that can be mechanically tested in vivo under a patchy knowledge of boundary conditions. Experimental data corresponding to the extension of a piece of skin located between two pads with displacement enslavement, represent input data to the numerical model. Data are reaction force on one pad and displacement field between the two pads and all around. The numerical model consists of a representation of the bi-material domain geometry with neo-hookean behaviors. The boundary conditions and loadings of the experimental extension test are imposed. The materials parameters have been identified by inverse method starting from a constrained cost function minimizing the difference between the calculated displacements field and experimental displacements field obtained by digital image correlation and taking into account the reaction force as a constraint. An analysis of the model sensitivity to material parameters is presented. [less ▲]

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See detailMechanical parameters identification of keloid and surrounding healthy skin using Digital Image Correlation measurements in vivo
Elouneg, Aflah; Sutula, Danas; Sensale, Marco UL et al

Scientific Conference (2019, December 09)

The human skin behaves as an elastic membrane initially prestressed but not uniformly. The presence of anatomical sites favorable to the appearance of some tumors, a keloid in our case, while other sites ... [more ▼]

The human skin behaves as an elastic membrane initially prestressed but not uniformly. The presence of anatomical sites favorable to the appearance of some tumors, a keloid in our case, while other sites never develop them attests to the importance of the mechanical environment of the tissue. Thus, a mechanical characterization of the tumored skin is necessary to understand the keloid expansion from a mechanical point of view. Our case study consists in modeling a bi-material structure composed of a keloid skin surrounded by healthy skin located on upper left arm of a young female. From the experimental measurements in vivo, by combining force sensor, displacement sensor and Digital Image Correlation techniques, we perform a mechanical analysis to characterize the mechanical stress fields over the entire area and on the interface ‘healthy skin/keloid skin’. Since the mechanical behavior of the tumorous skin is unknown, many physical models can be implemented and assessed very easily inside the specific digital software to fit with the real data. Once a set of mechanical parameters for both the healthy skin and the keloid skin are identified, the stress fields around the keloid are calculated. Next steps consist in determining matching preferential directions in order to define as precisely as possible the specifications of a device for preventing the growth of keloids. [less ▲]

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See detailJoint Scheduling and Precoding for Frame-Based Multigroup Multicasting in Satellite Communications
Bandi, Ashok UL; Shankar, Bhavani UL; Chatzinotas, Symeon UL et al

in Bandi, Ashok; Shankar, Bhavani; Chatzinotas, Symeon (Eds.) et al Joint Scheduling and Precoding for Frame-Based Multigroup Multicasting in Satellite Communications (2019, December 09)

Recent satellite standards enforce the coding of multiple users’ data in a frame. This transmission strategy mimics the well-known physical layer multigroup multicasting (MGMC). However, typical beam ... [more ▼]

Recent satellite standards enforce the coding of multiple users’ data in a frame. This transmission strategy mimics the well-known physical layer multigroup multicasting (MGMC). However, typical beam coverage with a large number of users and limited frame length lead to the scheduling of only a few users. Moreover, in emerging aggressive frequency reuse systems, scheduling is coupled with precoding. This is addressed in this work, through the joint design of scheduling and precoding for frame-based MGMC satellite systems. This aim is formulated as the maximization of the sum-rate under per beam power constraint and minimum SINR requirement of scheduled users. Further, a framework is proposed to transform the non-smooth SR objective with integer scheduling and nonconvex SINR constraints as a difference-of-convex problem that facilitates the joint update of scheduling and precoding. Therein, an efficient convex-concave procedure based algorithm is proposed. Finally, the gains (up to 50%) obtained by the jointed design over state-of-the-art methods is shown through Monte-Carlo simulations. [less ▲]

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See detailPsychiatric knowledge dissimination at international conferences (1860-1914): 'those who have the interest of science at heart, don't distinguish between nationalities'
Andersen, Eva UL

Scientific Conference (2019, December 06)

The amount of international conferences that were organised over the nineteenth century increased rapidly, and formed an ideal environment for discussions amongst peers and establishing knowledge ... [more ▼]

The amount of international conferences that were organised over the nineteenth century increased rapidly, and formed an ideal environment for discussions amongst peers and establishing knowledge transfers. Medical and psychiatric conferences were no exception. However, a study into psychiatric conferences on a larger scale has not yet been conducted. Adopting a transnational perspective is essential, and while this approach is gaining more attention from historians more generally, it is only slowly reaching the history of psychiatry. To gain insights into the (inter)national knowledge dissemination that happened within psychiatry, we will examine different organisational aspects such as the locations where conferences were held, its organisation and the subjects and questions that were included in the conference program, as well as studying the mutual connections between congresses and the connections between the participants. This will help to discover the key players and whether it was well-known psychiatrists that were most involved in these international conferences. These interwoven sub-questions will help to establish in how far an international community existed within psychiatry and thus if such international congresses were an epicentre of transnational knowledge dissemination or if they were rather a manifestation of national encounters. This research is based on the minutes and membership lists found within conference proceedings of the “Congrès internationale médecine mentale”, “Congrès international de neurologie, psychiatrie et de physiologie”, “Congrès international de l’assistance aux aliéné” and the “Congrès international de médecine” that also often included a section dedicated to psychiatry. These all took place between the 1860’s and the first decade of the twentieth century. [less ▲]

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See detailScaling of urban heat island & NO2 with urban population: a meta-analysis
Wei, Yufei UL; Caruso, Geoffrey UL; Lemoy, Rémi

Scientific Conference (2019, December 05)

Detailed reference viewed: 115 (7 UL)
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See detailAccommodation of non-nationals in Luxembourg
Wronska, Iwona; Murdock, Elke UL

Scientific Conference (2019, December 05)

The Grand Duchy of Luxembourg within its current borders was established in the end of 19th century. In the space of less than 150 years the population of this state more than doubled - largely ... [more ▼]

The Grand Duchy of Luxembourg within its current borders was established in the end of 19th century. In the space of less than 150 years the population of this state more than doubled - largely attributable to immigration. Today, 48% of the population are foreigners. We would like to argue that the current immigration policy of Luxembourg is based on the strategy of accommodation. We can identify three major pillars of this strategy. The first pillar creates welcome conditions to adaptation within the host society. The second pillar brings liberal provisions for naturalization and the third pillar offers open and generous admission of refugees. [less ▲]

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See detailA Lightweight Implementation of NTRU Prime for the Post-Quantum Internet of Things
Cheng, Hao UL; Dinu, Dumitru-Daniel; Groszschädl, Johann UL et al

in Laurent, Maryline; Giannetsos, Thanassis (Eds.) Information Security Theory and Practice, 13th IFIP WG 11.2 International Conference, WISTP 2019, Paris, France, December 11–12, 2019, Proceedings (2019, December)

The dawning era of quantum computing has initiated various initiatives for the standardization of post-quantum cryptosystems with the goal of (eventually) replacing RSA and ECC. NTRU Prime is a variant of ... [more ▼]

The dawning era of quantum computing has initiated various initiatives for the standardization of post-quantum cryptosystems with the goal of (eventually) replacing RSA and ECC. NTRU Prime is a variant of the classical NTRU cryptosystem that comes with a couple of tweaks to minimize the attack surface; most notably, it avoids rings with "worrisome" structure. This paper presents, to our knowledge, the first assembler-optimized implementation of Streamlined NTRU Prime for an 8-bit AVR microcontroller and shows that high-security lattice-based cryptography is feasible for small IoT devices. An encapsulation operation using parameters for 128-bit post-quantum security requires 8.2 million clock cycles when executed on an 8-bit ATmega1284 microcontroller. The decapsulation is approximately twice as costly and has an execution time of 15.6 million cycles. We achieved this performance through (i) new low-level software optimization techniques to accelerate Karatsuba-based polynomial multiplication on the 8-bit AVR platform and (ii) an efficient implementation of the coefficient modular reduction written in assembly language. The execution time of encapsulation and decapsulation is independent of secret data, which makes our software resistant against timing attacks. Finally, we assess the performance one could theoretically gain by using a so-called product-form polynomial as part of the secret key and discuss potential security implications. [less ▲]

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See detailCryptanalysis of CLT13 Multilinear Maps with Independent Slots
Coron, Jean-Sébastien UL; Notarnicola, Luca UL

in Advances in Cryptology – ASIACRYPT 2019, 25th International Conference on the Theory and Application of Cryptology and Information Security, Kobe, Japan, December 8–12, 2019, Proceedings, Part II (2019, December)

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See detailTemporal 3D Human Pose Estimation for Action Recognition from Arbitrary Viewpoints
Adel Musallam, Mohamed; Baptista, Renato UL; Al Ismaeil, Kassem UL et al

in 6th Annual Conf. on Computational Science & Computational Intelligence, Las Vegas 5-7 December 2019 (2019, December)

This work presents a new view-invariant action recognition system that is able to classify human actions by using a single RGB camera, including challenging camera viewpoints. Understanding actions from ... [more ▼]

This work presents a new view-invariant action recognition system that is able to classify human actions by using a single RGB camera, including challenging camera viewpoints. Understanding actions from different viewpoints remains an extremely challenging problem, due to depth ambiguities, occlusion, and a large variety of appearances and scenes. Moreover, using only the information from the 2D perspective gives different interpretations for the same action seen from different viewpoints. Our system operates in two subsequent stages. The first stage estimates the 2D human pose using a convolution neural network. In the next stage, the 2D human poses are lifted to 3D human poses, using a temporal convolution neural network that enforces the temporal coherence over the estimated 3D poses. The estimated 3D poses from different viewpoints are then aligned to the same camera reference frame. Finally, we propose to use a temporal convolution network-based classifier for cross-view action recognition. Our results show that we can achieve state of art view-invariant action recognition accuracy even for the challenging viewpoints by only using RGB videos, without pre-training on synthetic or motion capture data. [less ▲]

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See detailLinear system identification from ensemble snapshot observations
Aalto, Atte UL; Goncalves, Jorge UL

in Proceedings of the IEEE Conference on Decision and Control (2019, December)

Developments in transcriptomics techniques have caused a large demand in tailored computational methods for modelling gene expression dynamics from experimental data. Recently, so-called single-cell ... [more ▼]

Developments in transcriptomics techniques have caused a large demand in tailored computational methods for modelling gene expression dynamics from experimental data. Recently, so-called single-cell experiments have revolutionised genetic studies. These experiments yield gene expression data in single cell resolution for a large number of cells at a time. However, the cells are destroyed in the measurement process, and so the data consist of snapshots of an ensemble evolving over time, instead of time series. The problem studied in this article is how such data can be used in modelling gene regulatory dynamics. Two different paradigms are studied for linear system identification. The first is based on tracking the evolution of the distribution of cells over time. The second is based on the so-called pseudotime concept, identifying a common trajectory through the state space, along which cells propagate with different rates. Therefore, at any given time, the population contains cells in different stages of the trajectory. Resulting methods are compared in numerical experiments. [less ▲]

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See detailOn the Formal Structure of Rules in Conflict of Laws
Markovich, Réka UL

in Legal Knowledge and Information Systems 2019 (proceedings) (2019, December)

Law has different methods and principles to resolve conflicts between norms, most of these come from Roman Law, they are well-known and much discussed. There is a whole branch of law, though, which is ... [more ▼]

Law has different methods and principles to resolve conflicts between norms, most of these come from Roman Law, they are well-known and much discussed. There is a whole branch of law, though, which is much less discussed while having been created exactly in order to resolve special conflicts: conflict of laws. This system within Private International Law is dedicated to providing metarules in legal situations where more than one national legal systems’ rules could be applied: CoL rules indirectly settle the situation by declaring which one’s should. The formal representation of how these rules work contributes not only to the modelling of this branch of law but also provides methodologies for concerns arising from other conflicting normative systems, such as ethically sensitive situations where there are multiple stakeholders with different moral backgrounds. [less ▲]

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See detailAutomatic Software Tuning of Parallel Programs for Energy-Aware Executions
Varrette, Sébastien UL; Pinel, Frédéric UL; Kieffer, Emmanuel UL et al

in Proc. of 13th Intl. Conf. on Parallel Processing and Applied Mathematics (PPAM 2019) (2019, December)

For large scale systems, such as data centers, energy efficiency has proven to be key for reducing capital, operational expenses and environmental impact. Power drainage of a system is closely related to ... [more ▼]

For large scale systems, such as data centers, energy efficiency has proven to be key for reducing capital, operational expenses and environmental impact. Power drainage of a system is closely related to the type and characteristics of workload that the device is running. For this reason, this paper presents an automatic software tuning method for parallel program generation able to adapt and exploit the hardware features available on a target computing system such as an HPC facility or a cloud system in a better way than traditional compiler infrastructures. We propose a search based approach combining both exact methods and approximated heuristics evolving programs in order to find optimized configurations relying on an ever-increasing number of tunable knobs i.e., code transformation and execution options (such as the num- ber of OpenMP threads and/or the CPU frequency settings). The main objective is to outperform the configurations generated by traditional compiling infrastructures for selected KPIs i.e., performance, energy and power usage (for both for the CPU and DRAM), as well as the runtime. First experimental results tied to the local optimization phase of the proposed framework are encouraging, demonstrating between 8% and 41% improvement for all considered metrics on a reference benchmark- ing application (i.e., Linpack). This brings novel perspectives for the global optimization step currently under investigation within the presented framework, with the ambition to pave the way toward automatic tuning of energy-aware applications beyond the performance of the current state-of-the-art compiler infrastructures. [less ▲]

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See detailThe Impact of Human Mobility on Edge Data Center Deployment in Urban Environments
Vitello, Piergiorgio UL; Capponi, Andrea UL; Fiandrino, Claudio UL et al

in IEEE Global Communications Conference (GLOBECOM), Waikoloa, HI, USA, 2019 (2019, December)

Multi-access Edge Computing (MEC) brings storage and computational capabilities at the edge of the network into so-called Edge Data Centers (EDCs) to better low-latency applications. To this end ... [more ▼]

Multi-access Edge Computing (MEC) brings storage and computational capabilities at the edge of the network into so-called Edge Data Centers (EDCs) to better low-latency applications. To this end, effective placement of EDCs in urban environments is key for proper load balance and to minimize outages. In this paper, we specifically tackle this problem. To fully understand how the computational demand of EDCs varies, it is fundamental to analyze the complex dynamics of cities. Our work takes into account the mobility of citizens and their spatial patterns to estimate the optimal placement of MEC EDCs in urban environments in order to minimize outages. To this end, we propose and compare two heuristics. In particular, we present the mobility-aware deployment algorithm (MDA) that outperforms approaches that do not consider citizens mobility. Simulations are conducted in Luxembourg City by extending the CrowdSenSim simulator and show that efficient EDCs placement significantly reduces outages. [less ▲]

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See detailSafer UAV Piloting: A Robust Sense-and-Avoid Solution for Remotely Piloted Quadrotor UAVs in Complex Environments
Wang, Min UL; Voos, Holger UL

in Safer UAV Piloting: A Robust Sense-and-Avoid Solution for Remotely Piloted Quadrotor UAVs in Complex Environments (2019, December)

Current commercial UAVs are to a large extent remotely piloted by amateur human pilots. Due to lack of teleoperation experience or skills, they often drive the UAVs into collision. Therefore, in order to ... [more ▼]

Current commercial UAVs are to a large extent remotely piloted by amateur human pilots. Due to lack of teleoperation experience or skills, they often drive the UAVs into collision. Therefore, in order to ensure safety of the UAV as well as its surroundings, it is necessary for the UAV to boast the capability of detecting emergency situation and acting on its own when facing imminent threat. However, the majority of UAVs currently available in the market are not equipped with such capability. To fill in the gap, in this paper we present a complete sense-and-avoid solution for assisting unskilled pilots in ensuring a safe flight. Particularly, we propose a novel nonlinear vehicle control system which takes into account of sensor characteristics, an emergency evaluation policy and a novel optimization-based avoidance control strategy. The effectiveness of the proposed approach is demonstrated and validated in simulation with multiple moving objects. [less ▲]

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See detailUC Priced Oblivious Transfer with Purchase Statistics and Dynamic Pricing
Damodaran, Aditya Shyam Shankar UL; Dubovitskaya, Maria; Rial, Alfredo UL

in Progress in Cryptology – INDOCRYPT 2019 (2019, December)

Priced oblivious transfer (POT) is a cryptographic protocol that can be used to protect customer privacy in e-commerce applications. Namely, it allows a buyer to purchase an item from a seller without ... [more ▼]

Priced oblivious transfer (POT) is a cryptographic protocol that can be used to protect customer privacy in e-commerce applications. Namely, it allows a buyer to purchase an item from a seller without disclosing to the latter which item was purchased and at which price. Unfortunately, existing POT schemes have some drawbacks in terms of design and functionality. First, the design of existing POT schemes is not modular. Typically, a POT scheme extends a k-out-of-N oblivious transfer (OT) scheme by adding prices to the items. However, all POT schemes do not use OT as a black-box building block with certain security guarantees. Consequently, security of the OT scheme needs to be reanalyzed while proving security of the POT scheme, and it is not possible to swap the underlying OT scheme with any other OT scheme. Second, existing POT schemes do not allow the seller to obtain any kind of statistics about the buyer's purchases, which hinders customer and sales management. Moreover, the seller is not able to change the prices of items without restarting the protocol from scratch. We propose a POT scheme that addresses the aforementioned drawbacks. We prove the security of our POT in the UC framework. We modify a standard POT functionality to allow the seller to receive aggregate statistics about the buyer's purchases and to change prices dynamically. We present a modular construction for POT that realizes our functionality in the hybrid model. One of the building blocks is an ideal functionality for OT. Therefore, our protocol separates the tasks carried out by the underlying OT scheme from the additional tasks needed by a POT scheme. Thanks to that, our protocol is a good example of modular design and can be instantiated with any secure OT scheme as well as other building blocks without reanalyzing security from scratch. [less ▲]

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See detailMachine learning for physical-layer security: Attacks and SLP Countermeasures for Multiantenna Downlink Systems
Mayouche, Abderrahmane UL; Spano, Danilo; Tsinos, Christos UL et al

Scientific Conference (2019, December)

Most physical-layer security (PLS) work employ information theoretic metrics for performance analysis. In this paper, however, we investigate PLS from a signal processing point of view, where we rely on ... [more ▼]

Most physical-layer security (PLS) work employ information theoretic metrics for performance analysis. In this paper, however, we investigate PLS from a signal processing point of view, where we rely on bit-error rate (BER) at the eavesdropper (Eve) as a metric for information leakage. Meanwhile, recently, symbol-level precoding (SLP) has been shown to provide PLS gains as a new way for security. However, in this work, we introduce a machine learning (ML) based attack, where we show that even SLP schemes can be vulnerable to such attacks. Namely, this attack manifests when an eavesdropper (Eve) utilizes ML in order to learn the precoding pattern when precoded pilots are sent. With this ability, an Eve can decode data with favorable accuracy. As a countermeasure to this attack, we propose a novel precoding design. The proposed countermeasure yields high BER at the Eve, which makes symbol detection practically infeasible for the latter, thus providing physical-layer security between the base station (BS) and the users. In the numerical results, we validate both the attack and the countermeasure, and show that this gain in security can be achieved at the expense of only a small additional power consumption at the transmitter. [less ▲]

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See detailFrom tech to bench: Deep Learning pipeline for image segmentation of high-throughput high-content microscopy data
Garcia Santa Cruz, Beatriz UL; Jarazo, Javier UL; Saraiva, Claudia UL et al

Poster (2019, November 29)

Automation of biological image analysis is essential to boost biomedical research. The study of complex diseases such as neurodegenerative diseases calls for big amounts of data to build models towards ... [more ▼]

Automation of biological image analysis is essential to boost biomedical research. The study of complex diseases such as neurodegenerative diseases calls for big amounts of data to build models towards precision medicine. Such data acquisition is feasible in the context of high-throughput screening in which the quality of the results relays on the accuracy of image analysis. Although the state-of-the-art solutions for image segmentation employ deep learning approaches, the high cost of manual data curation is hampering the real use in current biomedical research laboratories. Here, we propose a pipeline that employs deep learning not only to conduct accurate segmentation but also to assist with the creation of high-quality datasets in a less time-consuming solution for the experts. Weakly-labelled datasets are becoming a common alternative as a starting point to develop real-world solutions. Traditional approaches based on classical multimedia signal processing were employed to generate a pipeline specifically optimized for the high-throughput screening images of iPSC fused with rosella biosensor. Such pipeline produced good segmentation results but with several inaccuracies. We employed the weakly-labelled masks produced in this pipeline to train a multiclass semantic segmentation CNN solution based on U-net architecture. Since a strong class imbalance was detected between the classes, we employed a class sensitive cost function: Dice coe!cient. Next, we evaluated the accuracy between the weakly-labelled data and the trained network segmentation using double-blind tests conducted by experts in cell biology with experience in this type of images; as well as traditional metrics to evaluate the quality of the segmentation using manually curated segmentations by cell biology experts. In all the evaluations the prediction of the neural network overcomes the weakly-labelled data quality segmentation. Another big handicap that complicates the use of deep learning solutions in wet lab environments is the lack of user-friendly tools for non-computational experts such as biologists. To complete our solution, we integrated the trained network on a GUI built on MATLAB environment with non-programming requirements for the user. This integration allows conducting semantic segmentation of microscopy images in a few seconds. In addition, thanks to the patch-based approach it can be employed in images with different sizes. Finally, the human-experts can correct the potential inaccuracies of the prediction in a simple interactive way which can be easily stored and employed to re-train the network to improve its accuracy. In conclusion, our solution focuses on two important bottlenecks to translate leading-edge technologies in computer vision to biomedical research: On one hand, the effortless obtention of high-quality datasets with expertise supervision taking advantage of the proven ability of our CNN solution to generalize from weakly-labelled inaccuracies. On the other hand, the ease of use provided by the GUI integration of our solution to both segment images and interact with the predicted output. Overall this approach looks promising for fast adaptability to new scenarios. [less ▲]

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See detailDeveloping Multilingual Pedagogies in Early Childhood: a review of the project MuLiPEC
Aleksic, Claudine UL; Aleksic, Gabrijela UL; Mortini, Simone UL et al

Scientific Conference (2019, November 27)

Developing Multilingual Pedagogies in Early Childhood: a review of the project The project MuLiPEC (2016-2019) addresses the need for multilingual pedagogies in early childhood education in Luxembourg. It ... [more ▼]

Developing Multilingual Pedagogies in Early Childhood: a review of the project The project MuLiPEC (2016-2019) addresses the need for multilingual pedagogies in early childhood education in Luxembourg. It offered a professional development (PD) course to develop the practitioners’ knowledge and skills in relation to multilingualism and effective pedagogies as well as their practices, and analysed the effects of the PD on the practitioners and the children’s languaging. We offered a first 15-hour course to 46 practitioners from formal and non-formal education settings. Of these, seven continued during one academic year. They were coached and took part in six network meetings where we discussed their practices. To analyse the results, we drew on observations of the PD and in the research settings, video-recorded activities, and interviews. The results show that all 46 participants opened up to multilingual education and deepened their understanding of multilingualism, language development and multilingual pedagogies. Furthermore, the seven focus practitioners implemented activities in multiple languages and deployed effective language supportive strategies. Five of them developed holistic and child-centred multilingual pedagogies. This paper presents these positive findings and raises questions related to the sustainability of PD course and the need to continue the implementation of these effective pedagogies. [less ▲]

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See detailDreaming of Constructivist Technology Integration Strategies in Future Teacher Students
Reuter, Robert UL; Busana, Gilbert UL

Scientific Conference (2019, November 27)

Based on previous experiences in preparing future teachers for technology integration (Reuter & Busana, 2017), and based on the recommendations from Kolb’s (2017) Triple E framework about effective uses ... [more ▼]

Based on previous experiences in preparing future teachers for technology integration (Reuter & Busana, 2017), and based on the recommendations from Kolb’s (2017) Triple E framework about effective uses of ICT in education, we have adapted the Educational Technology course in our Initial Teacher Training. Over the years, we have indeed observed that, when given the choice of the type of technology integration strategies, many students designed ICT-based learning and teaching scenarios that implemented a rather teacher-centred teaching model (Roblyer & Doering, 2013). These scenarios were often far from innovative nor did they implement the disruptive potential of ICT in education (Christensen, Horn & Johnson, 2008). In the winter semester 2018-2019 we thus decided to ask our students to design and develop constructivist technology integration scenarios. We assessed the success of this adaptation with the help of our own observations, the semester reports produced by our students and their answers to an end-of-semester course evaluation. In general, we saw that students were able to design rather attractive constructivist learning activities. We also observed that our students were quite surprised that such activities do not require complicated and expensive tools, but that they can be implemented with standard productivity tools. [less ▲]

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See detailA professional development course in translanguaging: Challenges and opportunities
Aleksic, Gabrijela UL; Dzoen, Bebic-Crestany

Scientific Conference (2019, November 27)

In Luxembourg, the new law in 2017 has declared multilingual early education mandatory. Not only that teachers need to help children develop their Luxembourgish, but also they need to familiarize them ... [more ▼]

In Luxembourg, the new law in 2017 has declared multilingual early education mandatory. Not only that teachers need to help children develop their Luxembourgish, but also they need to familiarize them with French and value their home languages. In order to support preschool teachers in this endeavour, our project aims to: (1) offer a professional development (PD) course in translanguaging, (2) involve children’s families to reinforce home-school collaboration, and (3) foster children’s cognitive, linguistic, and socio-emotional engagement in the classroom. We use a panoply of measures to reach our aims: focus groups and teacher questionnaires (aim 1), parent questionnaires and interviews (aim 2), a test in early literacy and numeracy in school and home languages, teacher assessment of children’s socio-emotional development and video observations with children (aim 3). Translanguaging, the main topic of our 22 hour PD course (June – December 2019), is the use of a full linguistic repertoire to make meaning (Otheguy, García, & Reid, 2015). In eight sessions, we explore multilingual ecology, parental involvement, and oracy and early literacy. We will present preliminary findings of the focus groups with teachers and tests in early literacy and numeracy in children’s home and school languages. Challenges and opportunities that emerged during the course will be explored as well. [less ▲]

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See detailA case study on the impact of masking moving objects on the camera pose regression with CNNs
Cimarelli, Claudio UL; Cazzato, Dario UL; Olivares Mendez, Miguel Angel UL et al

in 2019 16th IEEE International Conference on Advanced Video and Signal Based Surveillance (AVSS) (2019, November 25)

Robot self-localization is essential for operating autonomously in open environments. When cameras are the main source of information for retrieving the pose, numerous challenges are posed by the presence ... [more ▼]

Robot self-localization is essential for operating autonomously in open environments. When cameras are the main source of information for retrieving the pose, numerous challenges are posed by the presence of dynamic objects, due to occlusion and continuous changes in the appearance. Recent research on global localization methods focused on using a single (or multiple) Convolutional Neural Network (CNN) to estimate the 6 Degrees of Freedom (6-DoF) pose directly from a monocular camera image. In contrast with the classical approaches using engineered feature detector, CNNs are usually more robust to environmental changes in light and to occlusions in outdoor scenarios. This paper contains an attempt to empirically demonstrate the ability of CNNs to ignore dynamic elements, such as pedestrians or cars, through learning. For this purpose, we pre-process a dataset for pose localization with an object segmentation network, masking potentially moving objects. Hence, we compare the pose regression CNN trained and/or tested on the set of masked images and the original one. Experimental results show that the performances of the two training approaches are similar, with a slight reduction of the error when hiding occluding objects from the views. [less ▲]

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See detailDie Entstehung einer Hauptstadtregion als deutsch-belgische Beziehungsgeschichte
Brüll, Christoph UL

Scientific Conference (2019, November 22)

Vom 14. Mai - 23. Juli und vom 19. September - 31.Oktober 1972 fand zunächst im Kölner Museum Schnütgen und dann in den Brüsseler Musées Royaux d’Art et d’Histoire die bis heute größte Schau rheinisch ... [more ▼]

Vom 14. Mai - 23. Juli und vom 19. September - 31.Oktober 1972 fand zunächst im Kölner Museum Schnütgen und dann in den Brüsseler Musées Royaux d’Art et d’Histoire die bis heute größte Schau rheinisch-maasländischer Kunst statt. Unter dem Titel „Rhein und Maas. Kunst und Kultur 800-1400“ wurde sie zu einem großen Publikumserfolg, der auch in der Scientific Community der Kunsthistoriker einige Aufmerksamkeit erregte. Die Entstehung der Ausstellung sagt einiges über die Geschichte der Wissenschaftsbeziehungen zwischen Deutschland und Belgien seit 1945 aus, aber auch, so die Ausgangshypothese meines Beitrags, über die Veränderungen der in Belgien vorherrschenden Mental Maps von Deutschland seit der Verlagerung des politischen Schwerpunktes an den Rhein mit der Gründung der Bundesrepublik. Der belgische Deutschlanddiskurs knüpfte dabei durchaus an bereits bestehende Deutschlandbilder an, die gerade das Maasland als Zwischenraum inszenierten , doch kam durch das Zusammenrücken der westeuropäischen Länder im Zuge von Kaltem Krieg und beginnender europäischer Integration, gerade auch unter dem Signum des Abendlandes, eine neue Dimension ins Spiel. Mentalitätsgeschichtlich hob die rheinische Bonner Republik die durch den Ersten Weltkrieg hervorgerufene Distanz zwischen dem belgischen Staat und (West-)Deutschland auf, politikgeschichtlich fanden deutsche und belgische „Suche nach Sicherheit“ (E. Conze) ein enges Kooperationsfeld. Zum Zentrum der belgischen Aktivität im Rheinland wurde Köln, das nach dem durch die Wahl als Regierungssitz notwendig gewordenen Verlassen Bonns durch die belgischen Truppen in Deutschland 1950 zu deren neuem Hauptquartier wurde. Dort etablierte sich zudem rasch das Belgische Haus als Drehscheibe für politischen, konsularischen, aber auch kulturellen Austausch. Die Ausstellung „Rhein und Maas“ dient als Aufhänger für den Beitrag, der sowohl das Ende einer langen Nachkriegszeit als auch das Ankommen Belgiens in der Bonner Republik herausstellen kann. Auch die Anfang der 1970er Jahre erfolgten ersten gegenseitigen Staatsbesuche geben Aufschluss über Inszenierung und Wahrnehmung der Hauptstadtregion. Der Beitrag wirft somit eine beziehungsgeschichtliche Perspektive auf Bonn-Köln-Düsseldorf zwischen 1949 und den 1970er Jahren und fragt mit Bezug auf die Hauptstadtregion auf die belgische(n) Wahrnehmung(en) des Rheinischen, aber auch nach Rückwirkungen auf Brüssel als belgischer und europäischer Hauptstadt. [less ▲]

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See detailAu-delà du cours magistral: Vers des apprentissages autonomes et collaboratifs basés sur de « grandes questions »
Busana, Gilbert UL; Reuter, Robert UL

Scientific Conference (2019, November 22)

Nous enseignions depuis quelques années un cours de première année sur "l'éducation à l'ère numérique", dans la formation initiale des futur-e-s enseignant-e-s du fondamental, sous forme d’un cours ... [more ▼]

Nous enseignions depuis quelques années un cours de première année sur "l'éducation à l'ère numérique", dans la formation initiale des futur-e-s enseignant-e-s du fondamental, sous forme d’un cours magistral afin de véhiculer certaines connaissances théoriques et pratiques dans ce domaine. Cependant, nous avons observé au cours des dernières années que (1) de nombreux étudiants échouaient à l'examen et que (2) beaucoup d'entre eux, lorsqu'ils étaient en 4e année, avaient oublié la plupart des fondements. Ces considérations nous ont amenés à repenser et à remanier nos méthodes d'enseignement et notre façon d'évaluer les résultats d'apprentissage des étudiant-e-s. Après une première implémentation de notre nouvelle approche pédagogique combinant diverses méthodes actives d'apprentissage au semestre d’hiver 2018 (décrite et réfléchie dans Reuter & Busana, 2018), nous avons effectué quelques modifications basées (a) sur nos propres observations et réflexions ainsi que (b) sur les commentaires des étudiant-e-s tirées de l’évaluation du cours (organisée par notre université). Dès à présent, plutôt que de les faire travailler sur de « grandes questions » (c.-à-d. des questions pour lesquelles il n'y a pas de réponses simples et faciles à consulter) au cours des séances en présentiel, nous demandons maintenant à nos étudiant-e-s (1) de construire individuellement des connaissances en amont du séminaire sur base de ressources fournies ou tirés de recherches bibliographiques autonomes ; (2) de les présenter, discuter et développer de manière collaborative en petits groupes pendant les séminaires ; puis (3) de les partager et discuter avec nous et leurs pairs et finalement (4) de les conserver dans un portfolio numérique personnel. L’évaluation des apprentissages des étudiant-e-s est effectuée à l’aide de ce portfolio numérique en fin de semestre. [less ▲]

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See detailMono-static Automotive Joint Radar-Communications System
Dokhanchi, Sayed Hossein UL; Ottersten, Björn UL

Scientific Conference (2019, November 21)

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See detailToward fluid-structure-piezoelectric simulations applied to flow-induced energy harvesters
Hoareau, Christophe UL; Shang, Lan UL; Zilian, Andreas UL

Poster (2019, November 15)

The subject deals with the simulation of flow-induced energy harvesters. We focus in particular on the modelling of autonomous piezo-ceramic power generators to convert ambient fluid-flow energy into ... [more ▼]

The subject deals with the simulation of flow-induced energy harvesters. We focus in particular on the modelling of autonomous piezo-ceramic power generators to convert ambient fluid-flow energy into electrical energy. The vibrations of an immersed electromechanical structure with large amplitude have to be taken into account in that case. One challenge consists in modelling and predicting the nonlinear coupled dynamic behaviour for the improved design of such devices. The set of governing equations is expressed in integral form, using the method of weighted residuals, and discretized with finite elements using the open source package FEniCS. Preliminary results of separated problems using FEniCS will be detailed and discussed (e.g. Navier-Stokes with or without moving meshes, nonlinear elasticity, aeroelasticity and electromechanical coupling). The objective is to validate each problem independently before coupling all the phenomena in a monolithic framework. Those simulations involve nonlinearities at many levels of modeling. The perspective of using reduced order models to limit the computational cost (in time and memory) will be discussed in an outlook to this work. [less ▲]

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See detailAuthenticated Key Distribution: When the Coupon Collector is Your Enemy
Beunardeau, Marc; El Orche, Fatima Ezzahra UL; Maimut, Diana et al

in Innovative Security Solutions for Information Technology and Communications (2019, November 14)

We introduce new authenticated key exchange protocols which on the one hand do not resort to standard public key setups with corresponding assumptions of computationally hard problems, but on the other ... [more ▼]

We introduce new authenticated key exchange protocols which on the one hand do not resort to standard public key setups with corresponding assumptions of computationally hard problems, but on the other hand, are more efficient than distributing symmetric keys among the participants. To this end, we rely on a trusted central authority distributing key material whose size is independent of the total number of users, and which allows the users to obtain shared secret keys. We analyze the security of our construction, taking into account various attack models. Importantly, only symmetric primitives are needed in the protocol making it an alternative to quantum-safe key exchange protocols which rely on hardness assumptions. [less ▲]

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See detailOral History as a multimedia and multidimensional presentation challenge
Lambert, Douglas UL

Scientific Conference (2019, November 13)

Oral History is a multidisciplinary, multinational field based on a format of recorded, usually sit-down interviews, where the past is documented through personal narratives of life experience. In the ... [more ▼]

Oral History is a multidisciplinary, multinational field based on a format of recorded, usually sit-down interviews, where the past is documented through personal narratives of life experience. In the early 2000’s, a new approach to processing and managing oral histories was introduced based on timecode indexing made possible by software environments. This work can be referred to as Oral History Digital Indexing (OHDI), and it represents a suite of activities, tools, methods, and interfaces that have made oral histories more accessible both with and without transcripts, whilst reconnecting navigable text to original recordings for listening and watching. OHDI allows for oral history to be represented in visual, dynamic forms far more palatable to users than the previous default--a collection of transcripts. Pioneering OHDI work was done by Michael Frisch and The Randforce Associates, with whom the author worked with on a number of consulting projects between 2002 and 2018. The focus of these projects was distinctly on comprehensive timecode indexing, the use of annotation as an alternative to word-for-word transcription, and deployment of custom controlled vocabularies (CVs) organized visually as a spatially-meaningful content map. These CVs function like back-of-the-book term indexes providing better “front end” user access, but they have they also been adapted for research applications to organize sets of qualitative analysis codes. Through a post-doctoral research position at the University of Luxembourg, the author is introducing and integrating these OHDI methods into oral history development plans in Luxembourg. Several representative tools, interfaces, and CVs used to make oral histories more multimedia and multidimensional will be presented, all of which will be influential to the in-development “Luxembourgish Oral History Initiative.” [less ▲]

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See detailPost-collusion security and distance bounding
Mauw, Sjouke UL; Smith, Zachary Daniel UL; Trujillo Rasua, Rolando UL et al

in Post-collusion security and distance bounding (2019, November 11)

Verification of cryptographic protocols is traditionally built upon the assumption that participants have not revealed their long-term keys. However, in some cases, participants might collude to defeat ... [more ▼]

Verification of cryptographic protocols is traditionally built upon the assumption that participants have not revealed their long-term keys. However, in some cases, participants might collude to defeat some security goals, without revealing their long-term secrets. We develop a model based on multiset rewriting to reason about collusion in security protocols. We introduce the notion of postcollusion security, which verifies security properties claimed in sessions initiated after collusion occurred. We use post-collusion security to analyse terrorist fraud on protocols for securing physical proximity, known as distance-bounding protocols. In a terrorist fraud attack, agents collude to falsely prove proximity, whilst no further false proximity proof can be issued without further collusion. Our definitions and the Tamarin prover are used to develop a modular framework for verification of distance-bounding protocols that accounts for all types of attack from literature. We perform a survey of over 25 protocols, which include industrial protocols such as Mastercard’s contactless payment PayPass and NXP’s MIFARE Plus with proximity check. For the industrial protocols we confirm attacks, propose fixes, and deliver computer-verifiable security proofs of the repaired versions [less ▲]

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See detailPOSTER: Traffic Splitting to Counter Website Fingerprinting
de La Cadena Ramos, Augusto Wladimir UL; Mitseva, Asya UL; Pennekamp, Jan et al

Poster (2019, November 11)

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See detailThe 2004 Afghan Constitution and Islam Merits and Challenges
Al Hajjaji, Shams Al Din UL

Scientific Conference (2019, November 11)

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See detailWorkplace bullying exposure and subjective well-being – The mediating role of the frustration of the need for relatedness. A longitudinal six-wave study
Sischka, Philipp UL; Steffgen, Georges UL

Scientific Conference (2019, November 08)

Workplace bullying is a serious phenomenon that has serious detrimental effects on victim’s health, attitudes, and work-related behavior. Drawing on self-determination theory, we propose that bullying ... [more ▼]

Workplace bullying is a serious phenomenon that has serious detrimental effects on victim’s health, attitudes, and work-related behavior. Drawing on self-determination theory, we propose that bullying exposure thwarts employee’s need for relatedness with the result of decreased well-being. Studies examining these mechanisms used either a cross-sectional design (Trépanier et al., 2013) or a longitudinal design with (not theoretically justified) long time intervals (i.e., 12-month time lag; Trépanier et al., 2015). Therefore, the aim of our study was to test this mediation in a longitudinal design with much shorter time intervals (i.e. monthly), whether to see if the bullying exposure also shows short-term effects on well-being. A six-wave online survey design with monthly time lag was employed and data were collected among U.S. employees. The sample consists of 1,595 respondents (55.8% females, n=890, ageM = 36.9, ageSD =10.3). Workplace bullying exposure was assessed with the S-NAQ (Notelaers et al., 2018), frustration of the need for relatedness with the Psychological Needs Thwarting Scale (Bartholomew et al., 2011) and well-being with the WHO-5 well-being-index (Topp et al., 2015). Cross-lagged mediation analysis within a structural equation modeling framework confirmed the mediation model: Bullying exposure was significantly related to a change in frustration of relatedness and frustration of relatedness was significantly related to a change in well-being across all waves. The study findings advance the field through showing that bullying exposure has not only a long-term effect on well-being but also a short one, and that this effect is mediated through the frustration of relatedness. [less ▲]

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See detailDimensional and Social Comparison Effects on Domain-Specific Academic Self-Concepts and Interests with First- and Third-Grade Students
van der Westhuizen, Lindie UL; Arens, Katrin; Keller, Ulrich UL et al

Scientific Conference (2019, November 06)

Academic self-concepts (ASCs) are self-perceptions of one’s own academic abilities. The internal/external frame of reference (I/E) model (Marsh, 1986) explains the formation of domain-specific ASCs ... [more ▼]

Academic self-concepts (ASCs) are self-perceptions of one’s own academic abilities. The internal/external frame of reference (I/E) model (Marsh, 1986) explains the formation of domain-specific ASCs through a combination of social (i.e. comparing one’s achievement in one domain with the achievement of others in the same domain) and dimensional (i.e. comparing one’s achievement in one domain with one’s achievement in another domain) comparisons. This results into positive achievement-self-concept relations within the math and verbal domains, but into negative achievement-self-concept relations across these domains. The generalized internal/external frame of reference (GI/E) model (Möller, Müller-Kalthoff, Helm, Nagy, & Marsh, 2015) extends the I/E model to the formation of other domain-specific academic self-beliefs such as interest. Research on the validity of the (G)I/E model for elementary school children is limited, especially for first-graders. This study examined the associations between verbal and math achievement and corresponding domain-specific self-concepts and interests for first-graders and third-graders. Two fully representative Luxembourgish first-grader cohorts and two fully representative third-graders cohorts (N=21,192) were used. The analyses were based on structural equation modeling. The findings fully supported the (G)I/E model for third-graders: Achievement was positively related to self-concept and interest within matching domains. Negative relations were found between achievement and self-concept and between achievement and interest across domains. For first-graders, achievement was positively related to self-concept and interest within matching domains. However, the majority of cross-domain relations were non-significant, except for the negative path between math achievement and verbal interest. Hence, while the formation of domain-specific ASCs and interests seem to rely on social and dimensional comparisons for third-graders, only social comparisons seem to be in operation for first-graders. Gender and cohort invariance was established for both grade levels. The findings are discussed within the framework of ASC differentiation and dimensional comparison theory applied to elementary school students. [less ▲]

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