Die zweifache Rechtfertigung des ‚Bösewichts‘: Figurationen des Bösen bei Schiller

Scientific Conference (2022, June)

Les prédicteurs de la cyberchondrie durant la pandémie de Covid-19 : Une approche en apprentissage automatique supervisé

Scientific Conference (2022, May 31)

Introduction : La cyberchondrie se caractérise pas des recherches en ligne répétées et compulsives au sujet de la santé, résultant en une détresse et une augmentation de l’anxiété liée à la santé. Ce ... [more ▼]

Introduction : La cyberchondrie se caractérise pas des recherches en ligne répétées et compulsives au sujet de la santé, résultant en une détresse et une augmentation de l’anxiété liée à la santé. Ce comportement, considéré comme un problème de santé publique émergeant, pourrait être exacerbé par l’apparition de la pandémie de Covid-19. Cette étude vise à étudier les changements dans la gravité de la cyberchondrie durant la pandémie et d’identifier les prédicteurs de la cyberchondrie à ce moment. Méthode : Des données auto-rapportées sur la gravité de la cyberchondrie (avant et pendant la pandémie), le style d’attachement, les traits d’impulsivité, les symptômes somatiques, les peurs liées au Covid-19, l’anxiété liée à la santé, et l’intolérance à l’incertitude ont été collectées auprès de 725 participants. L’étude en ligne a été distribuée dans les pays européens francophones lors de la première vague de la pandémie. Résultats : Les facettes de détresse et d’interférence avec le fonctionnement de la cyberchondrie ont augmentés durant la pandémie, alors que la facette de réassurance a diminué. Lors des analyses de régression utilisant l’apprentissage automatique supervisé, les peurs liées au Covid-19 ainsi que l’anxiété liée à la santé ont émergés comme étant les prédicteurs les plus importants des facettes de détresse et d’interférence avec le fonctionnement de la cyberchondrie pendant la pandémie. Conclusion : Ces résultats mettent en exergue l’impact de la pandémie sur la cyberchondrie et identifie les facteurs qui devraient être investis pour prévenir et gérer la cyberchondrie lors d’une crise de santé publique. [less ▲]

On the Reduction of Computational Costs for Tungsten Powder Bed Processes

Scientific Conference (2022, May 31)

During the Discrete Element Method (DEM) representation of powder bed processes (e.g. tungsten oxide reduction, tungsten carbide synthesis, selective laser sintering) a numerical solution for each single ... [more ▼]

During the Discrete Element Method (DEM) representation of powder bed processes (e.g. tungsten oxide reduction, tungsten carbide synthesis, selective laser sintering) a numerical solution for each single particle is impractical due to the extremely high number of particles (e.g. 10^12). However, in such processes, particles in the vicinity of each other observe low gradients concerning their thermodynamic state. This characteristic can be exploited to avoid solving repeatedly numerically equivalent equation systems. This contribution presents two numerical methods aiming to reduce the computational costs of DEM approaches for the thermochemical conversion of powder beds. In the two methods after an appropriated numerical treatment, a group of particles under similar boundary conditions is substituted by a single-effective-entity. Consequently, the entire powder space is divided into sub-domains to be solved. The methods result in considerable lower number of equations that increase computational efficiency and enable feasible time simulations. The applications of the industrial synthesis of tungsten powders and the selective laser sintering (SLS) of powder metals are presented and discussed. [less ▲]

A Cybersecurity Incident: Who You Gonna Call?

Scientific Conference (2022, May 25)

Les tests d’intolérance alimentaire : une pratique commerciale déloyale ?

Scientific Conference (2022, May 25)

TriggerZoo: A Dataset of Android Applications Automatically Infected with Logic Bombs

in 19th International Conference on Mining Software Repositories, Data Showcase, (MSR 2022) (2022, May 23)

Many Android apps analyzers rely, among other techniques, on dynamic analysis to monitor their runtime behavior and detect potential security threats. However, malicious developers use subtle, though ... [more ▼]

Many Android apps analyzers rely, among other techniques, on dynamic analysis to monitor their runtime behavior and detect potential security threats. However, malicious developers use subtle, though efficient, techniques to bypass dynamic analyzers. Logic bombs are examples of popular techniques where the malicious code is triggered only under specific circumstances, challenging comprehensive dynamic analyses. The research community has proposed various approaches and tools to detect logic bombs. Unfortunately, rigorous assessment and fair comparison of state-of-the-art techniques are impossible due to the lack of ground truth. In this paper, we present TriggerZoo, a new dataset of 406 Android apps containing logic bombs and benign trigger-based behavior that we release only to the research community using authenticated API. These apps are real-world apps from Google Play that have been automatically infected by our tool AndroBomb. The injected pieces of code implementing the logic bombs cover a large pallet of realistic logic bomb types that we have manually characterized from a set of real logic bombs. Researchers can exploit this dataset as ground truth to assess their approaches and provide comparisons against other tools. [less ▲]

GraphCode2Vec: generic code embedding via lexical and program dependence analyses

in Proceedings of the 19th International Conference on Mining Software Repositories (2022, May 22)

Code embedding is a keystone in the application of machine learn- ing on several Software Engineering (SE) tasks. To effectively support a plethora of SE tasks, the embedding needs to capture program ... [more ▼]

Code embedding is a keystone in the application of machine learn- ing on several Software Engineering (SE) tasks. To effectively support a plethora of SE tasks, the embedding needs to capture program syntax and semantics in a way that is generic. To this end, we propose the first self-supervised pre-training approach (called GraphCode2Vec) which produces task-agnostic embedding of lexical and program dependence features. GraphCode2Vec achieves this via a synergistic combination of code analysis and Graph Neural Networks. GraphCode2Vec is generic, it allows pre-training, and it is applicable to several SE downstream tasks. We evaluate the effectiveness of GraphCode2Vec on four (4) tasks (method name prediction, solution classification, mutation testing and overfitted patch classification), and compare it with four (4) similarly generic code embedding baselines (Code2Seq, Code2Vec, CodeBERT, Graph- CodeBERT) and seven (7) task-specific, learning-based methods. In particular, GraphCode2Vec is more effective than both generic and task-specific learning-based baselines. It is also complementary and comparable to GraphCodeBERT (a larger and more complex model). We also demonstrate through a probing and ablation study that GraphCode2Vec learns lexical and program dependence features and that self-supervised pre-training improves effectiveness. [less ▲]

Difuzer: Uncovering Suspicious Hidden Sensitive Operations in Android Apps

in 44th International Conference on Software Engineering (ICSE 2022) (2022, May 21)

One prominent tactic used to keep malicious behavior from being detected during dynamic test campaigns is logic bombs, where malicious operations are triggered only when specific conditions are satisfied ... [more ▼]

One prominent tactic used to keep malicious behavior from being detected during dynamic test campaigns is logic bombs, where malicious operations are triggered only when specific conditions are satisfied. Defusing logic bombs remains an unsolved problem in the literature. In this work, we propose to investigate Suspicious Hidden Sensitive Operations (SHSOs) as a step towards triaging logic bombs. To that end, we develop a novel hybrid approach that combines static analysis and anomaly detection techniques to uncover SHSOs, which we predict as likely implementations of logic bombs. Concretely, Difuzer identifies SHSO entry-points using an instrumentation engine and an inter-procedural data-flow analysis. Then, it extracts trigger-specific features to characterize SHSOs and leverages One-Class SVM to implement an unsupervised learning model for detecting abnormal triggers. We evaluate our prototype and show that it yields a precision of 99.02% to detect SHSOs among which 29.7% are logic bombs. Difuzer outperforms the state-of-the-art in revealing more logic bombs while yielding less false positives in about one order of magnitude less time. All our artifacts are released to the community. [less ▲]

L'émission de radio "100 Jahre Ostbelgien"

Scientific Conference (2022, May 20)

Die unfreien Befreiten. Über die lange Heimkehr der sowjetischen ZwangsarbeiterInnen aus Luxemburg.

Scientific Conference (2022, May 17)

Inna Ganschow untersucht in ihrem Vortrag die verschiedenen Typen totaler Institutionen im Sinne Erving Goffmans auf dem Weg von ZwangsarbeiterInnen aus der Sowjetunion nach Luxemburg und zurück. Von den ... [more ▼]

Inna Ganschow untersucht in ihrem Vortrag die verschiedenen Typen totaler Institutionen im Sinne Erving Goffmans auf dem Weg von ZwangsarbeiterInnen aus der Sowjetunion nach Luxemburg und zurück. Von den nationalsozialistischen Durchgangs- und Kriegsgefangenenlagern über die luxemburgischen Werk- und Ostarbeiterlager bis hin zu den sowjetischen Sammel- und Filterlagern endete die lange Reise nach Hause oft nach einigen Monaten oder Jahren erneut in einem Lager oder einer Zwangsansiedlung. Die Repatriierung junger ukrainischer, weißrussischer und russischer Frauen wird anhand von erhaltenen Dokumenten aus erster Hand, verschiedenen Lager- und Betriebsunterlagen sowie Augenzeugenberichten rekonstruiert. Die Rückführung wird im Hinblick auf ihre Funktion analysiert, die eine Bestrafung, eine Belohnung oder ein Schutz sein konnte. [less ▲]

Traffic Steering for eMBB and uRLLC Coexistence in Open Radio Access Networks

in Traffic Steering for eMBB and uRLLC Coexistence in Open Radio Access Networks (2022, May 16)

Existing radio access network (RAN) architectures are lack of sufficient openness, flexibility, and intelligence to meet the diverse demands of emerging services in beyond 5G and 6G wireless networks ... [more ▼]

Existing radio access network (RAN) architectures are lack of sufficient openness, flexibility, and intelligence to meet the diverse demands of emerging services in beyond 5G and 6G wireless networks, including enhanced mobile broadband (eMBB) and ultra-reliable and low-latency (uRLLC). Open RAN (ORAN) is a promising paradigm that allows building a virtualized and intelligent architecture. In this paper, we focus on traffic steering (TS) scheme based on multi-connectivity (MC) and network slicing (NS) techniques to efficiently allocate heterogeneous network resources in “NextG” cellular networks. We formulate the RAN resource allocation problem to simultaneously maximize the weighted sum eMBB throughput and minimize the worst-user uRLLC latency subject to QoS requirements, and orthogonality, power, and limited fronthaul constraints. Since the formulated problem is categorized as a mixed integer … [less ▲]

The NIS 2.0 Directive - Lessons learnt or lagging behind? A legal perspective

Scientific Conference (2022, May 10)

Scanning the Past: A 3D Model of Trausch's Library

Scientific Conference (2022, May 05)

Today, modern geospatial technologies and methods are widely used in combination with the documentation and preservation of objects of importance to cultural heritage. In this setting, archeologists and ... [more ▼]

Today, modern geospatial technologies and methods are widely used in combination with the documentation and preservation of objects of importance to cultural heritage. In this setting, archeologists and historians alike benefit from the rapid technological developments over the past decades, which have resulted in instrumentation that allows the capture of real objects and the generation of accurate and precise three-dimensional (3D) digital representations, i.e. models, from these sensed data. Here, the object of interest is the villa of the late historian Professor Gilbert Trausch with its library, for which a virtual library should be created for the general public. The building is an 19th century townhouse located on Limpertsberg in the City of Luxembourg and contains a cellar, three floors as well as a loft. Of particular interest were the cellar, stair cases, the first (the location of Professor Trausch’s office) and second floors as most of the bookshelves are situated there. In line with state-of-the-art approaches for 3D building modelling, a broad spectrum of modern geospatial technologies including classical surveying, Global Navigation Satellite System (GNSS), digital close-range photogrammetry and terrestrial laser scanning were employed to capture the Villa Trausch and its 33 bookshelves, i.e. Trausch’s Library, in all its details, while providing all data in one homogeneous coordinate system. Models and more photo-realistic visualizations of the exterior and interior have been obtained using, e.g., indoor images captured during the scanning. These allowed us to explore different virtual reality (VR) pathways employed by the gaming industry, for the generation of a first VR experience of the building in the sense of a digital museum. Currently solutions for the development of a public virtual library using commercial providers are investigated. [less ▲]

The Best Space Resource is the One You Can Catch and Reuse

Poster (2022, May 03)

From the beginning of space exploration more than 60 years ago, only a few in-orbit objects have been removed or reused. In fact, the Kessler Syndrome states that the number of space debris is growing ... [more ▼]

From the beginning of space exploration more than 60 years ago, only a few in-orbit objects have been removed or reused. In fact, the Kessler Syndrome states that the number of space debris is growing exponentially [1], leaving unused uncooperative objects orbiting at high velocities at several altitudes, especially in Low-Earth Orbit (LEO). In other words, the situation brings up two main critical issues: not only a non-sustainable space environment for satellite missions, with orbit saturation, but also the creation of an unsafe place for future human-related space exploration missions. Active Debris Removal is a possible solution for tackling the problem of space debris. Despite being extremely challenging, catching autonomously and harmlessly an uncooperative object tumbling at high velocity demands reliability, compliance and robustness. The fruitful collaboration between industry and academia (Spacety Luxembourg - SnT-SpaceR research group at the University of Luxembourg), is leading to the cutting-edge concept of a two-step capturing mechanism. A first ‘soft capture’ ensures that the debris is received softly while dampening any vibrations generated during the contact. Then, a ‘hard capture’ secures the debris so that it would be deorbited or safely shipped for other orbits or space stations for reuse. Capturing debris and decommissioned in-orbit objects for recycling or reusing can be the anchor of new opportunities in space and beyond. Most of the objects in orbit can have aluminum parts, besides other beneficial materials among their subsystems, such as solar panels, antennas or electronics which can be reused. To maximize space resources reusability, it is important to not harm the target. Capturing solutions such as harpoons or rigid interfaces can cause damage to the targets, resulting in hardly exploitable resources, and even more smaller debris tumbling in orbit [2]. An application of the proposed capturing technology would be to collect defunct satellites and debris, thus contributing to a more sustainable environment in space, gathering those on a possible recycling orbit or to any future Space Station for recycling. References [1] Drmola J. and Hubik T., Kessler Syndrome: System Dynamics Model (2018), In-Space Policy, 44–45, 29–39 [2] Zhao P., Liu J. and Wu C., Survey on Research and Development of On-Orbit Active Debris Removal Methods (2020), Sci China Tech Sci, 63: 2188–2210 [less ▲]

Automated Handling of Anaphoric Ambiguity in Requirements: A Multi-solution Study

in In Proceedings of the 44th International Conference on Software Engineering (ICSE'22), Pittsburgh, PA, USA 22-27 May 2022 (2022, May)

Ambiguity is a pervasive issue in natural-language requirements. A common source of ambiguity in requirements is when a pronoun is anaphoric. In requirements engineering, anaphoric ambiguity occurs when a ... [more ▼]

Ambiguity is a pervasive issue in natural-language requirements. A common source of ambiguity in requirements is when a pronoun is anaphoric. In requirements engineering, anaphoric ambiguity occurs when a pronoun can plausibly refer to different entities and thus be interpreted differently by different readers. In this paper, we develop an accurate and practical automated approach for handling anaphoric ambiguity in requirements, addressing both ambiguity detection and anaphora interpretation. In view of the multiple competing natural language processing (NLP) and machine learning (ML) technologies that one can utilize, we simultaneously pursue six alternative solutions, empirically assessing each using a collection of ~1,350 industrial requirements. The alternative solution strategies that we consider are natural choices induced by the existing technologies; these choices frequently arise in other automation tasks involving natural-language requirements. A side-by-side empirical examination of these choices helps develop insights about the usefulness of different state-of-the-art NLP and ML technologies for addressing requirements engineering problems. For the ambiguity detection task, we observe that supervised ML outperforms both a large-scale language model, SpanBERT (a variant of BERT), as well as a solution assembled from off-the-shelf NLP coreference resolvers. In contrast, for anaphora interpretation, SpanBERT yields the most accurate solution. In our evaluation, (1) the best solution for anaphoric ambiguity detection has an average precision of ~60% and a recall of 100%, and (2) the best solution for anaphora interpretation (resolution) has an average success rate of ~98%. [less ▲]

Efficient Resource Scheduling and Optimization for Over-Loaded LEO-Terrestrial Networks

in Proceeding of IEEE ICC 2022 (2022, May)

Towards the next generation networks, low earth orbit (LEO) satellites have been considered as a promising component for beyond 5G networks. In this paper, we study downlink LEO-5G communication systems ... [more ▼]

Towards the next generation networks, low earth orbit (LEO) satellites have been considered as a promising component for beyond 5G networks. In this paper, we study downlink LEO-5G communication systems in a practical scenario, where the integrated LEO-terrestrial system is over-loaded by serving a number of terminals with high-volume traffic requests. Our goal is to optimize resource scheduling such that the amount of undelivered data and the number of unserved terminals can be minimized. Due to the inherent hardness of the formulated quadratic integer programming problem, the optimal algorithm requires unaffordable complexity. To solve the problem, we propose a near-optimal algorithm based on alternating direction method of multipliers (ADMM-HEU), which saves computational time by taking advantage of the distributed ADMM structure, and a low-complexity heuristic algorithm (LC-HEU), which is based on estimation and greedy methods. The results demonstrate the near-optimality of ADMM-HEU and the computational efficiency of LC-HEU compared to the benchmarks. [less ▲]

Effective Rate of RIS-aided Networks with Location and Phase Estimation Uncertainty

in Proceedings of IEEE Wireless Communications and Networking Conference (WCNC) (2022, May)

Dynamic Bandwidth Allocation and Edge Caching Optimization for Nonlinear Content Delivery through Flexible Multibeam Satellites

in IEEE International Conference on Communications (2022, May)

The next generation multibeam satellites open up a new way to design satellite communication channels with the full flexibility in bandwidth, transmit power and beam coverage management. In this paper, we ... [more ▼]

The next generation multibeam satellites open up a new way to design satellite communication channels with the full flexibility in bandwidth, transmit power and beam coverage management. In this paper, we exploit the flexible multibeam satellite capabilities and the geographical distribution of users to improve the performance of satellite-assisted edge caching systems. Our aim is to jointly optimize the bandwidth allocation in multibeam and caching decisions at the edge nodes to address two important problems: i) cache feeding time minimization and ii) cache hits maximization. To tackle the non-convexity of the joint optimization problem, we transform the original problem into a difference-of-convex (DC) form, which is then solved by the proposed iterative algorithm whose convergence to at least a local optimum is theoretically guaranteed. Furthermore, the effectiveness of the proposed design is evaluated under the realistic beams coverage of the satellite SES-14 and Movielens data set. Numerical results show that our proposed joint design can reduce the caching feeding time by 50% and increase the cache hit ratio (CHR) by 10% to 20% compared to existing solutions. Furthermore, we examine the impact of multispot beams and multicarrier wide-beam on the joint design and discuss potential research directions. [less ▲]

Efficient Online Testing for DNN-Enabled Systems using Surrogate-Assisted and Many-Objective Optimization

in Proceedings of the 44th International Conference on Software Engineering (ICSE ’22) (2022, May)

With the recent advances of Deep Neural Networks (DNNs) in real-world applications, such as Automated Driving Systems (ADS) for self-driving cars, ensuring the reliability and safety of such DNN- enabled ... [more ▼]

With the recent advances of Deep Neural Networks (DNNs) in real-world applications, such as Automated Driving Systems (ADS) for self-driving cars, ensuring the reliability and safety of such DNN- enabled Systems emerges as a fundamental topic in software testing. One of the essential testing phases of such DNN-enabled systems is online testing, where the system under test is embedded into a specific and often simulated application environment (e.g., a driving environment) and tested in a closed-loop mode in interaction with the environment. However, despite the importance of online testing for detecting safety violations, automatically generating new and diverse test data that lead to safety violations present the following challenges: (1) there can be many safety requirements to be considered at the same time, (2) running a high-fidelity simulator is often very computationally-intensive, and (3) the space of all possible test data that may trigger safety violations is too large to be exhaustively explored. In this paper, we address the challenges by proposing a novel approach, called SAMOTA (Surrogate-Assisted Many-Objective Testing Approach), extending existing many-objective search algorithms for test suite generation to efficiently utilize surrogate models that mimic the simulator, but are much less expensive to run. Empirical evaluation results on Pylot, an advanced ADS composed of multiple DNNs, using CARLA, a high-fidelity driving simulator, show that SAMOTA is significantly more effective and efficient at detecting unknown safety requirement violations than state-of-the-art many-objective test suite generation algorithms and random search. In other words, SAMOTA appears to be a key enabler technology for online testing in practice. [less ▲]

Downlink Throughput of Cell-Free Massive MIMO Systems Assisted by Hybrid Relay-Reflecting Intelligent Surfaces

Poster (2022, May)

We consider in this work a cell-free (CF) massive multiple-input-multiple-output (mMIMO) system where multiple hybrid relay-reflecting intelligent surfaces (HR-RIS) are deployed to assist communication ... [more ▼]

We consider in this work a cell-free (CF) massive multiple-input-multiple-output (mMIMO) system where multiple hybrid relay-reflecting intelligent surfaces (HR-RIS) are deployed to assist communication between access points and users. We first present the signal model and derive the minimum-mean-square-error estimate of the effective channels. We then present a comprehensive analysis for the considered HR-RIS-aided CF mMIMO system, where the closed-form expression of the downlink throughput is derived. The presented analytical results are also valid for conventional CF mMIMO systems, i.e., CF mMIMO systems with and without passive reconfigurable intelligent surfaces. Finally, the analytical derivations are verified by extensive numerical results. [less ▲]

A Collaborative System of Flying and Ground Robots with Universal Physical Coupling Interface (PCI), and the Potential Interactive Applications

Poster (2022, April 28)

Flying and ground robots complement each other in terms of their advantages and disadvantages. We propose a collaborative system combining flying and ground robots, using a universal physical coupling ... [more ▼]

Flying and ground robots complement each other in terms of their advantages and disadvantages. We propose a collaborative system combining flying and ground robots, using a universal physical coupling interface (PCI) that allows for momentary connections and disconnections between multiple robots/devices. The proposed system may better utilize the complementary advantages of both flying and ground robots. We also describe various potential scenarios where such a system could be of benefit to interact with humans - namely, remote field works and rescue missions, transportation, healthcare, and education. Finally, we discuss the opportunities and challenges of such systems and consider deeper questions which should be studied in future work. [less ▲]

Context, Prioritization, and Unexpectedness: Factors Influencing User Attitudes About Infographic and Comic Consent

in Web Conference Companion Volume (ACM) (2022, April 26)

Being asked to consent to data sharing is a ubiquitous experience in digital services - yet it is very rare to encounter a well designed consent experience. Considering the momentum and importance of a ... [more ▼]

Being asked to consent to data sharing is a ubiquitous experience in digital services - yet it is very rare to encounter a well designed consent experience. Considering the momentum and importance of a European data space where personal information freely and easily flows across organizations, sectors and Member States, solving the long-discussed thorny issue of "how to get consent right" cannot be postponed any further. In this paper, we describe the first findings from a study based on 24 semi-structured interviews investigating participants’ expectations and opinions toward consent in a data sharing scenario with a data trustee. We analyzed various dimensions of a consent form redesigned as a comic and an infographic, including language, information design, content and the writer-reader relationship. The results provide insights into the complexity of elements that should be considered when asking individuals to freely and mindfully disclose their data, especially sensitive information. [less ▲]

The positional value of education in the Americas: dynamics of inequality in labour market returns for highly unequal countries, 2000-2019

Scientific Conference (2022, April 22)

The article examines how the labour market value of education has changed in the context of the expansion of higher education. However, one drawback is understanding how it generates differences between ... [more ▼]

The article examines how the labour market value of education has changed in the context of the expansion of higher education. However, one drawback is understanding how it generates differences between high and low-skilled labour markets, particularly in contexts of high inequality and informality. This could be linked to specific mechanisms by which employers value educational credentials as signalled skills. Using the Luxembourg Income Study (LIS), we analyse trends over two decades in 11 American countries. Our results confirm the previous results for the claim that education has become increasingly positional, compared with the absolute model of education. However, we find that the relative gains in wages for workers with higher levels of education, as the pool of higher education graduates expand over time, increased only slightly in high-skilled occupations, while their relative gains decreased for lower-skilled occupations. This trend is present in both absolute and positional models of education. Moreover, when looking at the structure of labour markets in terms of the linkage between educational credentials and occupational groups, we higher the tertiary education specificity of occupations, the higher the earnings for workers with advantaged positions. These findings are consistent with processes of displacement of low-skilled workers due to increasing competition among highly educated workers, from the positional model of education. [less ▲]

Academic Profile Development: An Investigation of Differentiation Processes Based on Students' Achievement and Grade Level

Scientific Conference (2022, April 21)

Academic achievement profiles affect students’ further development, i.e., by informing educational and professional choices. However, there is a lack of knowledge on the mechanisms behind the development ... [more ▼]

Academic achievement profiles affect students’ further development, i.e., by informing educational and professional choices. However, there is a lack of knowledge on the mechanisms behind the development of academic profiles. For research on cognitive ability profiles, specifically differentiation processes, statistical tools have been developed. In the present article, we transfer these methods for differentiation research to academic achievement data. We examine differentiation depending on students’ general level of achievement and grade level in a large Luxembourgish student sample. Students’ achievements in German, French, and Math were assessed within the Luxembourg school monitoring program. We found more balanced academic profiles with increasing achievement level. We further found more balanced profiles with increasing grade level and a positive interaction effect. [less ▲]

A new R package for Finite Mixture Models with an application to pension systems

Scientific Conference (2022, April 20)

A performance-oriented comparative study of the Chapel high-productivity language to conventional programming environments

in PMAM '22: Proceedings of the Thirteenth International Workshop on Programming Models and Applications for Multicores and Manycores (2022, April 18)

The increase in complexity, diversity and scale of high performance computing environments, as well as the increasing sophistication of parallel applications and algorithms call for productivity-aware ... [more ▼]

The increase in complexity, diversity and scale of high performance computing environments, as well as the increasing sophistication of parallel applications and algorithms call for productivity-aware programming languages for high-performance computing. Among them, the Chapel programming language stands out as one of the more successful approaches based on the Partitioned Global Address Space programming model. Although Chapel is designed for productive parallel computing at scale, the question of its competitiveness with well-established conventional parallel programming environments arises. To this end, this work compares the performance of Chapel-based fractal generation on shared- and distributed-memory platforms with corresponding OpenMP and MPI+X implementations. The parallel computation of the Mandelbrot set is chosen as a test-case for its high degree of parallelism and its irregular workload. Experiments are performed on a cluster composed of 192 cores using the French national testbed Grid'5000. Chapel as well as its default tasking layer demonstrate high performance in shared-memory context, while Chapel competes with hybrid MPI+OpenMP in distributed-memory environment. [less ▲]

The effect of dataset confounding on predictions of deep neural networks for medical imaging

in Vol. 3 (2022): Proceedings of the Northern Lights Deep Learning Workshop 2022 (2022, April 18)

The use of Convolutional Neural Networks (CNN) in medical imaging has often outperformed previous solutions and even specialists, becoming a promising technology for Computer-aided-Diagnosis (CAD) systems ... [more ▼]

The use of Convolutional Neural Networks (CNN) in medical imaging has often outperformed previous solutions and even specialists, becoming a promising technology for Computer-aided-Diagnosis (CAD) systems. However, recent works suggested that CNN may have poor generalisation on new data, for instance, generated in different hospitals. Uncontrolled confounders have been proposed as a common reason. In this paper, we experimentally demonstrate the impact of confounding data in unknown scenarios. We assessed the effect of four confounding configurations: total, strong, light and balanced. We found the confounding effect is especially prominent in total confounder scenarios, while the effect on light and strong confounding scenarios may depend on the dataset robustness. Our findings indicate that the confounding effect is independent of the architecture employed. These findings might explain why models can report good metrics during the development stage but fail to translate to real-world settings. We highlight the need for thorough consideration of these commonly unattended aspects, to develop safer CNN-based CAD systems. [less ▲]

Sustainability and Circular Economy in Learning Factories – Case Studies

in SSRN (2022, April 11)

Since the mitigation of climate change is one of the biggest challenges to face on a global scale, the topic has become more relevant also in industrial context. Learning factories have proven to be ... [more ▼]

Since the mitigation of climate change is one of the biggest challenges to face on a global scale, the topic has become more relevant also in industrial context. Learning factories have proven to be suitable environments to address and convey competencies to tackle industrial challenges in an interactive way. Hence, several learning factories are already dealing with sustainability topics in various use cases. This paper strives to present a state of the art of sustainability and circular economy in learning factories. Therefore, a classification framework is developed based on the state of the art of several learning factories and existing literature regarding the topic. This framework is then used to systematically describe the different activities regarding sustainability and circular economy that are currently ongoing in learning factories worldwide. This can be used to get an idea about the different aspects of the topic and how to address them, but furthermore also offers assistance to identify “blind spots” which could and should be addressed in learning factories in the future. [less ▲]

Differential Phase Compensation in Over-the-air Precoding Test-bed for a Multi-beam Satellite

Scientific Conference (2022, April 10)

This article presents a closed-loop differential phase compensation system for a precoding-enabled multibeam satellite forward link and its validation by live experiments on a GEO satellite scenario. The ... [more ▼]

This article presents a closed-loop differential phase compensation system for a precoding-enabled multibeam satellite forward link and its validation by live experiments on a GEO satellite scenario. The precoding operation avoids inter-beam interference and maximizes the spectrum efficiency by full frequency reuse as an alternative to the traditional two-color or four-color reuse methods proposed in the DVB-S2 standard. However, the satellite payload introduces differential phase and frequency impairments, which can degrade the precoding performance. This work describes the implementation of the differential phase and frequency tracking and compensation loop in an end-to-end testbed over a multibeam satellite system with independent local oscillators. The developed system performs end-to-end real-time communication over the satellite link, including channel measurements and precompensation. Results are validated by an over-the-air demonstration using two beams of the SES-14 multibeam satellite. Each beam is transmitted by independent transponders, which results in differential frequency and phase offsets due to the transponder undisciplined local oscillators. This phase offset makes it impossible to use precoding without the phase compensation loop. We prove that the implemented system can successfully track and compensate the differential phase and frequency to improve precoding performance. [less ▲]

Musique à vent pendant l'occupation nazie au Luxembourg de 1940 à 1944

Scientific Conference (2022, April 09)

Intuitive human-robot interaction using augmented reality: A simulation study on KUKA IIWA robot

in SSRN (2022, April 06)

trajeR, une nouvelle librairie R pour les modèles de mélange pour données longitundinales

Scientific Conference (2022, April 04)

Empathy in Design Scale: Development and Initial Insights

in Proceedings of the Extended Abstracts of the 2022 CHI Conference on Human Factors in Computing Systems (2022, April)

Empathy towards users is crucial to the design of user-centered technologies and services. Previous research focused on defining empathy and its role in the design process for triggering empathy for end ... [more ▼]

Empathy towards users is crucial to the design of user-centered technologies and services. Previous research focused on defining empathy and its role in the design process for triggering empathy for end-users. However, there is a lack of empathy measurement instruments in design. Most previous work focused on designers, overlooking the need for other stakeholders to develop empathy towards the users to break organizational silos and deliver high-quality user-centered services and products. In this contribution, we share the preliminary stages of the development of an empathy scale for service design. We build on empathy literature from psychology and design to define 18 items representing four empathy dimensions. We report on the definition of these dimensions and their underlying items, and present preliminary studies in which we reviewed the first version of the scale with experts and stakeholders. [less ▲]

Habilyzer: A User-Driven Open-Ended Sensor Kit for Office Workers

in Proceedings of the Extended Abstracts of the 2022 CHI Conference on Human Factors in Computing Systems (2022, April)

Office work presents health and wellbeing challenges, triggered by working habits or environmental factors. While technological interventions gain popularity in the workplace, they often fall short of ... [more ▼]

Office work presents health and wellbeing challenges, triggered by working habits or environmental factors. While technological interventions gain popularity in the workplace, they often fall short of acknowledging personal needs. Building on approaches from personal informatics, we present our vision on the use of user-driven, situated sensor probes in an office context and how the community might deal with complex yet timely questions around the use of data to empower people in becoming explorers of their own habits and experiences. We demonstrate Habilyzer, an open-ended sensor toolkit for office workers, which enables user-driven explorations in self-tracking their work routines. This research contributes an alternative approach to improving working habits and vitality in the workplace, moving from solution-oriented technologies to inquiry-enabling tools. Through this demonstration, we also aim to trigger discussions on the use of sensors and data in the office context, in the light of privacy, consent and data ownership. [less ▲]

EduCHI 2022 - 4th Annual Symposium on HCI Education

in Proceedings of the CHI 2022 Conference on Human Factors in Computing Systems (2022, April)

EduCHI 2022 will bring together an international community of scholars, practitioners, and researchers to shape the future of Human-Computer Interaction (HCI) education. Held as part of the CHI 2022 ... [more ▼]

EduCHI 2022 will bring together an international community of scholars, practitioners, and researchers to shape the future of Human-Computer Interaction (HCI) education. Held as part of the CHI 2022 conference, the two-day symposium will feature in- teractive discussions about trends, curricula, pedagogies, teaching practices, and current and future challenges facing HCI educators. In addition to providing a platform to share curriculum plans and teaching materials, EduCHI 2022 will also provide opportunities for HCI educators to learn new instructional strategies and deepen their pedagogical knowledge. [less ▲]

Fontana: Triggering Physical Activity and Social Connectedness through an Interactive Water Installation

in Proceedings of the Extended Abstracts of the 2022 CHI Conference on Human Factors in Computing Systems (2022, April)

Promoting healthy and active lifestyles is an important objective for many governing agencies. The design of active urban environments can be an effective tool to encourage more active behaviors and water ... [more ▼]

Promoting healthy and active lifestyles is an important objective for many governing agencies. The design of active urban environments can be an effective tool to encourage more active behaviors and water features can attract people, improving their experience of the urban space. To explore the potential of these concepts, we designed Fontana; an interactive public installation that aims to stimulate physical activity and social connectedness in the urban outdoor space, using the multidimensional attractiveness of water. We focus on the use of embedded interactive technology to promote physical activity, using water as a linking element between users. Adopting a research-through-design approach, we explored how such installations can nudge people into an active behavior while additionally strengthening social connectedness, using inclusive design principles. We report on insights gathered through this case study and findings of a preliminary user test, discussing the implications of this work for design researchers and practitioners. [less ▲]

Habilyzer: Empowering Office Workers to Investigate their Working Habits using an Open-Ended Sensor Kit

in Proceedings of the Extended Abstracts of the 2022 CHI Conference on Human Factors in Computing Systems (2022, April)

Office work presents health and wellbeing challenges, triggered by unhealthy working habits or environmental factors. While technologies for vitality in the office context gain popularity, they are often ... [more ▼]

Office work presents health and wellbeing challenges, triggered by unhealthy working habits or environmental factors. While technologies for vitality in the office context gain popularity, they are often solution-focused and fall short in acknowledging personal needs. Building on approaches from personal informatics, we see value in opening up the design space of tracking and sensing technologies for office workers. We designed and deployed an open-ended sensor kit and conducted two complementary studies to investigate the value of empowering office workers to investigate their own working habits. Findings show that Habilyzer triggers curiosity about working habits, and wireless sensors contribute to inquire into those habits, possibly supported by additional tools. We contribute new insights into how an open-ended sensor kit can be designed to support self-tracking practices and underlying reflections in the underexplored context of office work. It is an alternative approach to workplace vitality, moving from solution-oriented technologies to inquiry-enabling tools. [less ▲]

Conceptualising the Legal Notion of ‘State of the Art’ in the Context of IT Security

in Friedewald, Michael; Krenn, Stephan; Schiffner, Stefan (Eds.) et al Privacy and Identity Management. Between Data Protection and Security (2022, March 31)

The History of Cross-Border Cooperation: some historiographical remarks

Scientific Conference (2022, March 24)

What is Cross-Border Cooperation? How to write the History of Cross-Border Cooperation? The contribution explores the historiography in the field and presents two case studies (Euregio Meuse-Rhine and ... [more ▼]

What is Cross-Border Cooperation? How to write the History of Cross-Border Cooperation? The contribution explores the historiography in the field and presents two case studies (Euregio Meuse-Rhine and Europäische Vereinigung Eifel-Ardennen). It focusses on the sources that could be used for such a history and on difficulties regarding archival research. [less ▲]

La relecture entre pairs : un levier de motivation de la pratique de l’écrit

Scientific Conference (2022, March 17)

Les enseignants corrigent et donnent des conseils d’amélioration à leurs apprenants, mais les commentaires des enseignants sont parfois mal compris (Cole, Coats, Lentell 1986 ; Smith 1997), alors que la ... [more ▼]

Les enseignants corrigent et donnent des conseils d’amélioration à leurs apprenants, mais les commentaires des enseignants sont parfois mal compris (Cole, Coats, Lentell 1986 ; Smith 1997), alors que la relecture entre pairs apporte un échange avec moins de pression (Lejot 2017). Cet échange se fait à un niveau de hiérarchie égal et facilite la négociation de sens des éléments du texte. Néanmoins, certains élèves pointent le manque de qualification des pairs pour remplacer les commentaires des professeurs dans l’enseignement supérieur (Rollinson 2005). Cette démarche trouve toute sa force pour les doctorants. Mis en place sur un semestre, ce système fermé de relecture et de commentaires reçus en boucle est bénéfique et motivant pour ces derniers. Dans les ateliers interdisciplinaires sur les compétences transversales et en l'occurrence celle de l'écrit académique, les doctorants soulignent l’énergie, la réflexion commune et le soutien que leur a apporté la relecture de texte d'un pair et d'être eux-mêmes relus (Lejot 2017). Relire est formateur et être compris par des chercheurs pairs fait faire un grand pas en termes de cohérence d'écriture et d'argumentation bien articulée à ces groupes des écoles doctorales. [less ▲]

Die Bedeutung der Schule für Gesundheit und Wohlbe- finden von Schülerinnen und Schülern: Ergebnisse der HBSC Surveys 2018 in Luxemburg

Scientific Conference (2022, March 10)

Neben der Familie ist die Schule für Kinder und Jugendliche ein wichtiges Umfeld. Hier verbringen sie einen großen Teil des Tages, hier treffen sie ihre Freunde, und ihre schulischen Leistungen bestimmen ... [more ▼]

Neben der Familie ist die Schule für Kinder und Jugendliche ein wichtiges Umfeld. Hier verbringen sie einen großen Teil des Tages, hier treffen sie ihre Freunde, und ihre schulischen Leistungen bestimmen wesentlich mit, welchen beruflichen Weg sie später einschlagen können. Dementsprechend hat die Schule als sozialer Kontext einen großen Einfluss auch auf das Wohlbefinden und gesundheitliche Befindlichkeiten der Schüler. Positive schulische Erfahrungen können eine Ressource für Wohlbefinden sein, negative Erfahrungen können die psychische und physische Gesundheit beeinträchtigen. Da es sich bei HBSC um eine Befragung handelt, die in der Schule durchgeführt wird und da die Schule ein wichtiges soziales Umfeld ist, werden auch mehrere Fragen zur Schule gestellt. Im Vortrag werden zunächst aktuelle Ergebnisse aus Luxemburg zum schulischen Kontext präsentiert und international eingeordnet. So wird schon seit mehreren Befragungen erhoben, ob die Schüler die Schule mögen, ob sie sich durch die Schularbeit gestresst fühlen und wie sie die Beziehungen zu ihren Klassenkameraden und den Lehrern bewerten und ob sie viel auf der Ebene der Klasse und der Schule mitbestimmen können. In einem zweiten Schritt wird mit Hilfe einer Clusteranalyse untersucht, ob es typische Konstellationen gibt, d. h. Gruppen von Schülern, die sich in ihren Schulerfahrungen möglichst stark ähneln. Aus der HBSC-Studie ist bekannt, dass es zahlreiche Zusammenhänge zwischen diesen Erfahrungen gibt. Wenn solche kohärenten Gruppen identifiziert werden können, dann kann eine darauf basierende Typologie helfen, die komplexen Zusammenhänge zwischen zahlreichen Variablen in komprimierter Form darzustellen. Im konkreten Fall wurden 4 schulbezogene Einstellungen und Bewertungen dazu genutzt, um solche Gruppen zu identifizieren. Diese Gruppen/Cluster werden zunächst anhand der Variablen beschrieben, die zur Gruppenbildung genutzt wurden. Die Analyse zeigt, dass es bezüglich der Schulerfahrungen fünf in sich homogene Cluster gibt. Cluster 1, in dem sich der größte Anteil der Schüler (28.8%) befindet, ist durch allgemein positive Schulerfahrungen gekennzeichnet. Die Schüler in dieser Gruppe mögen die Schule, sie berichten von einem guten Klassenklima und sie geben an, kaum durch die Schularbeit gestresst zu sein. Darüber hinaus berichten diese Schüler über ein gutes Verhältnis zu ihren Lehrern. Cluster 2 ist durch Schüler gekennzeichnet, deren Schulerfahrungen überwiegend positiv sind (sie mögen die Schule und sie haben ein gutes Verhältnis zu den Mitschülern und Lehrern), die sich aber durch die Schularbeit gestresst fühlen, was sich negativ auf ihr allgemeines Wohlbefinden auswirkt. Cluster 3 zeichnet sich durch Schüler aus, die über ein geringes Maß an Stress berichten und insgesamt durchschnittliche Werte für die schulbezogenen Variablen wie Beziehungen zu ihrem Lehrer und das Klassenklima aufweisen. In Cluster 4 befinden sich die Schüler, die viel Schulstress erfahren, relativ schlechte Beziehungen zu ihren Lehrern haben und die Schule im Allgemeinen nicht mögen. Allerdings berichten diese Schüler von einem guten Klassenklima. Dieses Cluster umfasst 14.7% der Schüler und ist damit das kleinste Cluster. Cluster 5 besteht aus Schülern mit durchweg negativen Schulerfahrungen und ist damit das Gegenteil von Cluster 1. Die Schüler in Cluster 5 haben viel Schulstress, sind nicht gerne in der Schule und berichten von schlechteren Beziehungen zu ihren Lehrern und Mitschülern im Vergleich zu den Schülern in den anderen Clustern. Die weitere Beschreibung der Cluster mit Hilfe von soziodemografischen Variablen, anderen schulbezogenen Variablen und gesundheitsbezogenen Ergebnisvariablen wird zeigen, dass die gefundenen Gruppen in sich kohärent sind bezüglich der schulbezogenen Variablen, und dass sie zudem mit gesundheitsbezogenen und mit soziodemografischen Variablen korrelieren. [less ▲]

Validierung und psychometrische Analyse automatisch generierter Mathematikaufgaben im Bereich Zahlen und Operationen

Scientific Conference (2022, March 09)

Subjektives Wohlbefinden in der 5. und 9. Schulklasse: gibt es einen Zusammenhang mit dem Bildungsweg und der schulischen Leistung?

Scientific Conference (2022, March 09)

Der Bildungsauftrag unserer heutigen Wissensgesellschaft vereint ein vielseitiges Spektrum an Kompetenzen, die den Schüler*innen vermittelt werden sollen. Die Lernziele beinhalten nicht nur akademischen ... [more ▼]

Der Bildungsauftrag unserer heutigen Wissensgesellschaft vereint ein vielseitiges Spektrum an Kompetenzen, die den Schüler*innen vermittelt werden sollen. Die Lernziele beinhalten nicht nur akademischen Erfolg, sondern auch schulisches Wohlbefinden. In der Bildungsforschung haben affektive und sozio-emotionale Faktoren sowie deren Einfluss auf das Erreichen von Lernzielen über die letzten Jahrzehnte an Interesse gewonnen (s.a. Hascher et al., 2018). Subjektives Wohlbefinden (SWB) ist ein komplexes, multidimensionales Phänomen, welches emotionale, soziale und kognitive Facetten umfasst (Hascher & Edlinger, 2009). Das SWB wird als Grundlage für erfolgreiches Lernen betrachtet (Hascher & Hagenauer, 2011), wobei der Zusammenhang je nach Entwicklungsstadium der Schüler*innen variieren kann. Ergebnisse einer Metaanalyse (Bücker et al., 2018) zeigten eine statistisch signifikante mittlere Effektstärke für den Zusammenhang zwischen SWB und Leistung, wobei diese Ergebnisse über verschiedene Ebenen soziodemografischer Merkmale, SWB-Domäne und Indikatoren der Leistung hinweg stabil waren. Außerdem zeigten Gutman und Voraus (2012) in einer längsschnittlichen Studie mit einer Kohorte von Schüler*innen zwischen 7 und 13 Jahren, schwache bis mittlere Korrelationen zwischen unterschiedlichen Dimensionen des Wohlbefindens und aktueller sowie späterer akademischer Leistung. In dieser Studie haben wir den Zusammenhang zwischen verschiedenen Dimensionen des SWB und standardisierten Kompetenztestergebnissen zu verschiedenen Zeitpunkten (5. und 9. Schulkasse) untersucht. Ein erstes Ziel bestand darin, die Unterschiede des Wohlbefindens in Bezug auf das Entwicklungsstadium zu untersuchen, wobei wir auch den Einfluss von Klassenwiederholung und Schulzweig betrachteten. Ein weiteres Ziel der Studie bestand darin, den Zusammenhang zwischen SWB und Leistung unter Berücksichtigung sozio-demografischer Variablen zu ermitteln. Die Ergebnisse basieren auf den Daten der gesamte Kohorte von Fünft- und Neuntklässler*innen (N=5159 bzw. N=6279), die im Rahmen des nationalen Schulmonitoring (Luxembourg School Monitoring Programm „Épreuves Standardisées“; Martin et al., 2015) im November 2018 in Luxemburg erhoben wurden. Im Rahmen dieser Erhebung wurden sowohl standardisierte Schulleistungstests als auch ein Fragebogen zu soziodemographischen und sozio-emotionalen Aspekten durchgeführt. Vier Domäne des SWB wurden erfasst: Selbstkonzept, Schulangst, soziale- sowie emotionale Inklusion. Die standardisierten Leistungstests umfassten Leseverstehen in Deutsch und Französisch sowie Mathematik. Zusätzlich wurden über einen Schüler- oder Elternfragebogen weitere sozio-demographische Merkmale erfasst. Der Zusammenhang zwischen SWB und Entwicklungsstadium (Schulklasse) unter Einbeziehung von Klassenwiederholung und Schulzweig wurde mittels zwei mixed model Analysen überprüft. Die Ergebnisse zeigten, dass Schüler*innen in der 5. Klasse höhere Werte von SWB angaben als Schüler*innen in der 9. Klasse, F(8,121164)=180.61, p<.001. Zusätzlich wurde das SWB negativ beeinflusst durch Klassenwiederholung, F(8, 63989)=17.75, p<.001. Neuntklässler*innen in anspruchsvolleren Schulzweigen gaben höhere Werte von SWB an als Schüler*innen in niedrigeren Schulzweigen, F(2,40219)=15.71, p<001. Die Schulleistung wurde über eine schrittweise Regression vorhergesagt: zunächst wurden sozio-demographische Hintergrundvariable (Geschlecht, Migrationshintergrund, HISEI der Eltern) dem Model hinzugefügt und, in einem zweiten Schritt, Indikatoren des SWB. Die Ergebnisse zeigten, dass in der 5. Klasse 13% und in der 9. Klasse 19% der Varianz in der Schulleistung durch soziodemografische Variablen vorausgesagt werden kann. Sowohl für Fünft- als auch für Neuntklässler*innen, erklärten die Dimensionen des SWB zusätzliche 6% bzw. 4% der Varianz. Die Ergebnisse dieser Studie zeigten, dass Entwicklungsstadium, Klassenwiederholung und Schulzweig einen Einfluß auf das SWB der Schüler*innen haben. Darüber hinaus zeigten die Ergebnisse, dass das SWB über soziodemografische Merkmale hinaus zur Erklärung der schulischen Leistung beiträgt. In Anbetracht ihrer Ergebnisse, kann diese Studie auch die Diskussion um Klassenwiederholung als pädagogische Intervention und um die Praxis der Aufgliederung von Schüler*innen nach Leistungsniveau innerhalb und zwischen Schulformen bereichern. Während sich die meisten Studien zu den Effekten dieser Interventionen auf die schulische Leistung konzentrierten, zeigt die vorliegende Studie, dass diese Maßnahmen auch das SWB betreffen. Weitere (längsschnittliche) Studien könnten darauf eingehen, inwieweit es letztendlich zu einem kumulativen Effekt auf die schulische Leistung kommen kann oder ob und inwiefern das SWB den Zusammenhang zwischen diesen Faktoren und der schulischen Leistung beeinflussen kann. [less ▲]

Are Value-Added Scores Stable Enough for High-Stakes Decisions?

Scientific Conference (2022, March)

Theoretical Background: Can we quantify the effectiveness of a teacher or a school with a single number? Researchers in the field of value-added (VA) models may argue just that (e.g., Chetty et al., 2014 ... [more ▼]

Theoretical Background: Can we quantify the effectiveness of a teacher or a school with a single number? Researchers in the field of value-added (VA) models may argue just that (e.g., Chetty et al., 2014; Kane et al., 2013). VA models are widely used for accountability purposes in education and quantify the value a teacher or a school adds to their students’ achievement. For this purpose, these models predict achievement over time and attempt to control for factors that cannot be influenced by schools or teachers (i.e., sociodemographic & sociocultural background). Following this logic, what is left must be due to teacher or school differences (see, e.g., Braun, 2005). To utilize VA models for high-stakes decision-making (e.g., teachers’ tenure, the allocation of funding), these models would need to be highly stable over time. School-level stability over time, however, has hardly been researched at all and the resulting findings are mixed, with some studies indicating high stability of school VA scores over time (Ferrão, 2012; Thomas et al., 2007) and others reporting a lack of stability (e.g., Gorard et al., 2013; Perry, 2016). Furthermore, as there is no consensus on which variables to use as independent or dependent variables in VA models (Everson, 2017; Levy et al., 2019), the stability of VA could vary between different outcome measures (e.g., language or mathematics). If VA models lack stability over time and across outcome measures, their use as the primary information for high-stakes decision-making is in question, and the inferences drawn from them could be compromised. Questions: With these uncertainties in mind, we examine the stability of school VA model scores over time and investigate the differences between language and mathematics achievement as outcome variables. Additionally, we demonstrate the real-life implications of (in)stable VA scores for single schools and point out an alternative, more constructive use of school VA models in educational research. Method: To study the stability of VA scores on school level over time and across outcomes, we drew on a sample of 146 primary schools, using representative longitudinal data from the standardized achievement tests of the Luxembourg School Monitoring Programme (LUCET, 2021). These schools included a heterogeneous and multilingual sample of 7016 students. To determine the stability of VA scores in the subject of mathematics and in languages over time, we based our analysis on two longitudinal datasets (from 2015 to 2017 and from 2017 to 2019, respectively) and generated two VA scores per dataset, one for language and one for mathematics achievement. We further analyzed how many schools displayed stable VA scores in the respective outcomes over two years, and compared the rank correlations of VA scores between language and mathematics achievement as an outcome variable. Results and Their Significance: Only 34-38 % of the schools showed stable VA scores from grade 1 to 3 with moderate rank correlations of r = .37 with language and r = .34 with mathematics achievement. We therefore discourage using VA models as the only information for high-stakes educational decisions. Nonetheless, we argue that VA models could be employed to find genuinely effective teaching or school practices—especially in heterogeneous student populations, such as Luxembourg, in which educational disparities are an important topic already in primary school (Hoffmann et al., 2018). Consequently, we contrast the school climate and instructional quality, which might be a driver of the differences between schools with stable high vs. low VA scores. Literature Braun, H. (2005). Using student progress to evaluate teachers: A primer on value-added models. Educational Testing Service. Chetty, R., Friedman, J. N., & Rockoff, J. E. (2014). Measuring the impacts of teachers I: Evaluating bias in teacher value-added estimates. American Economic Review, 104(9), 2593–2632. https://doi.org/10.1257/aer.104.9.2593 Everson, K. C. (2017). Value-added modeling and educational accountability: Are we answering the real questions? Review of Educational Research, 87(1), 35–70. https://doi.org/10.3102/0034654316637199 Ferrão, M. E. (2012). On the stability of value added indicators. Quality & Quantity, 46(2), 627–637. https://doi.org/10.1007/s11135-010-9417-6 Gorard, S., Hordosy, R., & Siddiqui, N. (2013). How unstable are “school effects” assessed by a value-added technique? International Education Studies, 6(1), 1–9. https://doi.org/10.5539/ies.v6n1p1 Kane, T. J., McCaffrey, D. F., Miller, T., & Staiger, D. O. (2013). Have We Identified Effective Teachers? Validating Measures of Effective Teaching Using Random Assignment. Research Paper. MET Project. Bill & Melinda Gates Foundation. https://files.eric.ed.gov/fulltext/ED540959.pdf Levy, J., Brunner, M., Keller, U., & Fischbach, A. (2019). Methodological issues in value-added modeling: An international review from 26 countries. Educational Assessment, Evaluation and Accountability, 31(3), 257–287. https://doi.org/10.1007/s11092-019-09303-w LUCET. (2021). Épreuves Standardisées (ÉpStan). https://epstan.lu Perry, T. (2016). English value-added measures: Examining the limitations of school performance measurement. British Educational Research Journal, 42(6), 1056–1080. https://doi.org/10.1002/berj.3247 Thomas, S., Peng, W. J., & Gray, J. (2007). Modelling patterns of improvement over time: Value added trends in English secondary school performance across ten cohorts. Oxford Review of Education, 33(3), 261–295. https://doi.org/10.1080/03054980701366116 [less ▲]

Making History Together: Participation in Museums

in Sonnabend, Gaby; Guy, Thewes (Eds.) Narratives in History Museums – Reflections and Perspectives (2022, March)

Provably Solving the Hidden Subset Sum Problem via Statistical Learning

in Mathematical Cryptology (2022, March), 1

At Crypto ’99, Nguyen and Stern described a lattice based algorithm for solving the hidden subset sum problem, a variant of the classical subset sum problem where the n weights are also hidden. As an ... [more ▼]

At Crypto ’99, Nguyen and Stern described a lattice based algorithm for solving the hidden subset sum problem, a variant of the classical subset sum problem where the n weights are also hidden. As an application, they showed how to break the Boyko et al. fast generator of random pairs (x, g x(mod p)). The Nguyen-Stern algorithm works quite well in practice for moderate values of n, but its complexity is exponential in n. A polynomial-time variant was recently described at Crypto 2020, based on a multivariate technique, but the approach is heuristic only. In this paper, we describe a proven polynomial-time algorithm for solving the hidden subset-sum problem, based on statistical learning. In addition, we show that the statistical approach is also quite efficient in practice: using the FastICA algorithm, we can reach n = 250 in reasonable time. [less ▲]

Interactive Narratives and Transmedia Storytelling: An Insight on Digital Exhibitions

in Sonnabend, Gaby; Thewes, Guy (Eds.) Narratives in History Museums – Reflections and Perspectives (2022, March)

The delicate balance between expansion, innovation and maintenance of the Luxembourg Telephone Network

Scientific Conference (2022, February 24)

Since its establishment in 1885, the Luxembourg telephone network was characterised by bottlenecks in network expansion, which were in the course of the 20th century to be remedied by new cables ... [more ▼]

Since its establishment in 1885, the Luxembourg telephone network was characterised by bottlenecks in network expansion, which were in the course of the 20th century to be remedied by new cables (expansion) and new distribution technology (innovation). However, the envisioned expansion was repeatedly slowed down by a lack of trained technical staff and resources. For example, requests for new connections had repeatedly to be rejected and already planned expansion measures had to be postponed. Due to the one-sided focus of government and Luxembourg Post (PTT) administration on network expansion, the maintenance and repair of the network suffered at the same time, so that more frequent defects occurred. At the same time did the repair of defects tie up human and material resources that were then not available for expansion works. The PTT was thus confronted with a constant balancing act between the expansion and modernisation of the network and its maintenance, with the management level prioritising expansion and innovation. The problem was particularly virulent during the rapid expansion of telephony in the 1960s and 70s, but the paper will trace the fundamental conflict of interests for the first one hundred years of telephony in Luxembourg. The paper draws on legal documents and PTT reports to show how the construction, expansion and maintenance of the telephone network was envisioned, and how the shortage of technical staff and resources hampered the smooth operation of the system. [less ▲]

Discussion of an algorithm to transfer arbitrary shear connector load-slip curves into an effective shear resistance

in Kolloquiumsband - 23 DASt-Forschungskolloquium (2022, February 22)

The RFCS research project REDUCE (Project No. 710040) investigated dismountable shear connections with preloaded bolts. These connectors have in most cases a slip capacity greater than 6 mm and show a ... [more ▼]

The RFCS research project REDUCE (Project No. 710040) investigated dismountable shear connections with preloaded bolts. These connectors have in most cases a slip capacity greater than 6 mm and show a monotonic increasing nonlinear load-slip behaviour without plastic plateau and failure of the bolt in shear. Current design procedures of steel-concrete composite beams are largely based on the implementation of headed shear studs, which exhibit a rather different load-slip behaviour with a pronounced plastic niveau. Thus, a question turned out, which compression force can be activated by the shear connection in the concrete girder of a composite beam and how can the respective ultimate bending capacity be determined. Hence, this contribution presents an analytical algorithm to estimate the occurring compression force in the concrete girder when demountable shear connectors are used. The proposed algorithm bases on the actual measured load-slip curve of the shear connection and the expected slip along the beam, which is estimated for each single connector to later determine the compression force in the concrete girder. In addition to the explanation of the “general algorithm”, assumptions for practical use have been made for the slip distribution to simplify the calculation of the compression force and an effective shear resistance P_Rd,eff. [less ▲]

THE EVOLUTION OF THERMAL DISTORTION AND STRESSES AT MACRO SCALE FOR METAL ADDITIVELY MANUFACTURED PART

Scientific Conference (2022, February 05)

[1] R.K. Ganeriwala, M. Strantza, W.E. King, B. Clausen, T.Q. Phan, L.E. Levine, D.W. Brown, N.E. Hodge, Evaluation of a thermomechanical modelfor prediction of residual stress during laser powder bed ... [more ▼]

[1] R.K. Ganeriwala, M. Strantza, W.E. King, B. Clausen, T.Q. Phan, L.E. Levine, D.W. Brown, N.E. Hodge, Evaluation of a thermomechanical modelfor prediction of residual stress during laser powder bed fusion of Ti-6Al- 4V, Additive Manufacturing(2019), Vol. 27., 489–502. [2] M. S. Alnaes, J. Blechta, J. Hake, A. Johansson, B. Kehlet, A. Logg, C. Richardson, J. Ring, M. E. Rognes and G. N. Wells, The FEniCS Project Version 1.5, Archive of Numerical Software(2015), Vol. 3., 100:9–23. [less ▲]