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See detailNonstandard n-distances based on certain geometric constructions
Kiss, Gergely; Marichal, Jean-Luc UL

E-print/Working paper (2021)

The concept of n-distance was recently introduced to generalize the classical definition of distance to functions of n arguments. In this paper we investigate this concept through a number of examples ... [more ▼]

The concept of n-distance was recently introduced to generalize the classical definition of distance to functions of n arguments. In this paper we investigate this concept through a number of examples based on certain geometrical constructions. In particular, our study shows to which extent the computation of the best constant associated with an n-distance may sometimes be difficult and tricky. It also reveals that two important graph theoretical concepts, namely the total length of the Euclidean Steiner tree and the total length of the minimal spanning tree constructed on n points, are instances of n-distances. [less ▲]

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See detailLabor Market Effects of Technology Shocks biased Toward the Traded Sector
Bertinelli, Luisito UL; cardi, Olivier; restout, Romain

in Department of Economics and Management - Discussion Paper (2021), 2021-15

Motivated by recent evidence pointing at an increasing contribution of asymmetric shocks across sectors to economic fluctuations, we explore the labor market effects of technology shocks biased toward the ... [more ▼]

Motivated by recent evidence pointing at an increasing contribution of asymmetric shocks across sectors to economic fluctuations, we explore the labor market effects of technology shocks biased toward the traded sector. Our VAR evidence for seventeen OECD countries reveals that the non-traded sector alone drives the increase in total hours worked following a technology shock that increases permanently traded relative to non-traded TFP. The shock generates a reallocation of labor toward the non-traded sector which contributes to 35% on average of the rise in non-traded hours worked. Both labor reallocation and variations in labor income shares are found empirically connected with factor-biased technological change. Our quantitative analysis shows that a two-sector open economy model with flexible prices can reproduce the labor market effects we document empirically once we allow for imperfect mobility of labor, gross substitutability between home- and foreign-produced traded goods, and factor-biased technological change. When calibrating the model to country-specific data, its ability to account for the cross-country reallocation and redistributive effects we estimate increases once we let factor-biased technological change vary between sectors and across countries. [less ▲]

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See detailApproaches for completing metabolic networks through metabolite damage and repair discovery
Griffith, Corey UL; Walvekar, Adhish UL; Linster, Carole UL

in Current Opinion in Systems Biology (2021), 28

Metabolites are prone to damage, either via enzymatic side reactions, which collectively form the underground metabolism, or via spontaneous chemical reactions. The resulting non-canonical metabolites ... [more ▼]

Metabolites are prone to damage, either via enzymatic side reactions, which collectively form the underground metabolism, or via spontaneous chemical reactions. The resulting non-canonical metabolites that can be toxic, are mended by dedicated “metabolite repair enzymes.” Deficiencies in the latter can cause severe disease in humans, whereas inclusion of repair enzymes in metabolically engineered systems can improve the production yield of value-added chemicals. The metabolite damage and repair loops are typically not yet included in metabolic reconstructions and it is likely that many remain to be discovered. Here, we review strategies and associated challenges for unveiling non-canonical metabolites and metabolite repair enzymes, including systematic approaches based on high-resolution mass spectrometry, metabolome-wide side-activity prediction, as well as high-throughput substrate and phenotypic screens. [less ▲]

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See detailTumour immune evasion is promoted by actin cytoskeleton-driven polarization of inhibitory signals to the immunological synapse
Wurzer, Hannah Gertrud Andrea UL

Doctoral thesis (2021)

Natural killer (NK) cells are innate immune cells that are the first line of defence against infection and malignant transformation. They have the ability to recognize and destroy virally infected or ... [more ▼]

Natural killer (NK) cells are innate immune cells that are the first line of defence against infection and malignant transformation. They have the ability to recognize and destroy virally infected or cancerous cells without the need for priming or activation and therefore represent a promising target for new immunotherapeutic approaches against cancer. For their anti-tumour function, NK cells rely on actin cytoskeleton remodelling, in particular during the formation of the lytic immunological synapse (IS) with prospective target cells. The IS is characterized by an extensive assembly of filamentous actin (F-actin) and polarization of the NK cell for directed delivery of lytic granules. However, the IS allows bi-directional exchange of information, and anti-tumour effector functions of NK cells are often impaired through inhibitory signals that are transmitted through killer immunoglobulin-like receptors (KIRs) or the CD94/NK group 2 member A (NKG2A) heterodimeric receptor. Moreover, resistant tumour cells can polarize their own actin cytoskeleton to the IS in a process called actin response, enforcing the formation of an evasion IS or actin response-IS (AR-IS). This PhD thesis focuses on the evaluation of associated resistance mechanisms that occur at the AR-IS, the conservation of these processes and their translation to in vivo models of cancer. For this purpose, individual cancer-NK cell conjugates were analysed by high-throughput imaging flow cytometry (IFC) to investigate the accumulation of F-actin at the IS and the distribution of inhibitory and activating ligands in relation to the IS. The AR was associated with a wider synaptic cleft, prominent recruitment of predominantly inhibitory ligands and inhibition of NK cell-induced target cell death. Further, the AR could also be applied to cytotoxic T lymphocyte (CTL) attack during antigen specific IS formation. To explore the in vivo relevance of the AR, modified murine cancer cell lines were established that allowed for the evaluation of impact of the AR on tumour progression, the tumour immune landscape, immune cell activation and exhaustion. Reduction of the actin response was associated with a reduction of tumour volume, enhanced infiltration of CTLs and NK cells and higher numbers of effector T cells. In summary, this study reports a novel, highly conserved immune-escape mechanism that exploits fast remodelling of the actin cytoskeleton of cancer cells to induce clustering of inhibitory ligands at the AR-IS and prevent NK cell activation. This AR is characterized by fine synaptic filopodia-like protrusions (SFPs) that are decorated with inhibitory ligands and probe the surface of the NK cell in addition to providing a steric hindrance for NK cell attachment to target cells. In our pre-clinical mouse model, we could demonstrate that a reduction of the AR results in the restoration of anti-tumour immunity. Understanding the mechanism that enables or initiates the AR and finding new ways to target this mechanism has the potential to improve cancer immunotherapy, especially for NK cell-based approaches. [less ▲]

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See detailThe factor structure of mathematical abilities in Luxembourg’s national school monitoring: Its stability over elementary school and relations to, gender, language background, and SES
Sonnleitner, Philipp UL; Hornung, Caroline UL

Scientific Conference (2021, July)

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

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

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See detailQuand les e-pétitions influencent-elles la décision politique ? Une analyse du système de pétitions électroniques de la Chambre des députés du Luxembourg
Kies, Raphaël UL; Seidenthal, Sven UL

in Participations: Revue de sciences sociales sur la démocratie et la citoyenneté (2021), 3(28), 177-202

Dans cet article, nous présentons l’une des premières analyses à étudier de manière systématique les facteurs expliquant le degré d’appropriation par un gouvernement des demandes exprimées dans les e ... [more ▼]

Dans cet article, nous présentons l’une des premières analyses à étudier de manière systématique les facteurs expliquant le degré d’appropriation par un gouvernement des demandes exprimées dans les e-pétitions qui lui sont soumises. Cette analyse se base sur l’ensemble des e-pétitions ayant obtenu les 4 500 signatures requises pour donner lieu à un débat public à la Chambre des députés du Luxembourg. Les hypothèses testées pour expliquer les variations dans le niveau d’appropriation des e-pétitions par le gouvernement ont été : 1) la compatibilité avec l’agenda du gouvernement, 2) la compétence du gouvernement pour traiter les e-pétitions en question, 3) la nature consensuelle (ou non)de l’e-pétition, 4) le nombre de signatures en sa faveur, 5) sa visibilité médiatique, et 6) le statut de son initiateur. Conformément à nos attentes, nous avons observé que les probabilités qu’une e-pétition soit prise en considération par le gouvernement sont liées à essentiellement trois facteurs : 1) la compatibilité avec l’agenda du gouvernement, 2) la compétence du gouvernement et 3) l’accord du gouvernement avec les revendications des pétitionnaires. Les autres facteurs, tels que le soutien populaire ou médiatique de l’e-pétition, sa thématique ou bien les coûts de sa réalisation, apparaissent peu significatifs. [less ▲]

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See detailIntroduction. La participation politique en ligne au révélateur du pétitionnement électronique
Contamin, Jean-Gabriel; Kies, Raphaël UL; Paye, Olivier et al

in Participations: Revue de sciences sociales sur la démocratie et la citoyenneté (2021), 3(28), 7-45

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See detailVirtual reality gaming for pain distraction - Investigation of attentional and psychophysiological effects
Holl, Elisabeth UL; Rischer, Katharina Miriam UL; Battistutta, Layla UL et al

Scientific Conference (2021, May)

Virtual reality has been shown to be a powerful method to divert attention away from pain (Malloy & Milling, 2010) and has been used successfully to temporally relieve patients from pain in clinical ... [more ▼]

Virtual reality has been shown to be a powerful method to divert attention away from pain (Malloy & Milling, 2010) and has been used successfully to temporally relieve patients from pain in clinical settings. However, little is known about the underlying attentional processes involved in pain processing in virtual reality. Therefore, as one of the first studies, this project investigates the role of especially cognitive factors influencing distraction from pain. N = 90 healthy participants played the video game Subnautica in two virtual reality conditions (high vs. low cognitive load). To assess the distraction effect, pain thresholds and psychophysiological measures were assessed during play. Additionally, executive functions and self-reported measures on, e.g., presence, simulation sickness and pain-related subjects were assessed. Results suggest that interactive virtual reality games are a potential tool to alter pain processing, regardless of the level of cognitive load. [less ▲]

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See detailMotivation to Play Scale (MOPS): Measuring Gaming Motivation With a Comprehensive Instrument
Holl, Elisabeth UL; Wagener, Gary Lee UL; Melzer, André UL

Scientific Conference (2021, May)

With the growing interest in gaming, the motivation why people play has become a focus of research. Scales assessing gaming motivation are mostly based on either motivation theories or on self-constructed ... [more ▼]

With the growing interest in gaming, the motivation why people play has become a focus of research. Scales assessing gaming motivation are mostly based on either motivation theories or on self-constructed items adapted to specific genres. Despite the amount of existing scales, measures often lack validation or leave out important and novel motives. Therefore, the Motivation to Play Scale (MOPS), a work-in-progress project, aims at identifying a holistic instrument validated by systematically collecting and evaluating already existing items. A first evaluation survey (N = 555) resulted in preliminary version of the MOPS measuring 14 gaming motives (e.g., competition, escapism) using 59 items (α = .94). [less ▲]

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See detailInvestigating the role of individual differences in the hypoalgesic response to a virtual reality game: An exploratory analysis
Rischer, Katharina Miriam UL; Barcatta, Katharina; Battistutta, Layla UL et al

Scientific Conference (2021, March)

Introduction: Virtual reality (VR) has been shown to be a powerful method of redirecting attention away from pain and is increasingly used in clinical settings as a therapeutic tool for pain treatment ... [more ▼]

Introduction: Virtual reality (VR) has been shown to be a powerful method of redirecting attention away from pain and is increasingly used in clinical settings as a therapeutic tool for pain treatment. Yet, little is known about the underlying factors that modulate the size of the hypoalgesic response to a VR game, such as cognitive load and inter-individual differences in self-reported pain-related cognitions, emotion regulation habits, gaming skills, and executive functions. Methods: 90 healthy participants played two versions of the VR game 'Subnautica', differing in cognitive load (low load vs. high load). In the low load condition, participants navigated along a predefined route. In the high load condition, participants additionally memorized a series of single digits presented along the route. Pain heat thresholds as well as psychophysiological measures (ECG, EDA) were recorded during a passive control condition (in VR) prior to, as well as during, the two interactive sessions. In addition, participants completed several psychological questionnaires and different executive functioning tasks prior to the VR sessions. Results: Pain thresholds were significantly higher in the two interactive VR sessions when compared to the passive control condition, whereas the cognitive load of the game had no effect on pain thresholds. Individual differences in pain-related cognitions, prepotent response inhibition abilities and the level of emotional awareness reported by female participants, but not the level of gaming skills, influenced the size of the hypoalgesic effect. Discussion: In line with a growing body of studies, we observed a robust hypoalgesic response to playing a VR game, highlighting once more the potential of VR as a tool for pain reduction. Importantly, the hypoalgesic effect was not dependent on the participants’ level of gaming skills or the cognitive load of the game, suggesting that the sensory properties of the VR game were sufficient to change the processing of pain. [less ▲]

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See detailRandomization as Mitigation of Directed Timing Inference Based Attacks on Time-Triggered Real-Time Systems with Task Replication
Krüger, Kristin; Vreman, Nils; Pates, Richard et al

in LITES: Leibnitz Transactions on Embedded Systems (2020)

Time-triggered real-time systems achieve deterministic behavior using schedules that are constructed offline, based on scheduling constraints. Their deterministic behavior makes time-triggered systems ... [more ▼]

Time-triggered real-time systems achieve deterministic behavior using schedules that are constructed offline, based on scheduling constraints. Their deterministic behavior makes time-triggered systems suitable for usage in safety-critical environments, like avionics. However, this determinism also allows attackers to fine-tune attacks that can be carried out after studying the behavior of the system through side channels, targeting safety-critical victim tasks. Replication – i.e., the execution of task variants across different cores – is inherently able to tolerate both accidental and malicious faults (i.e. attacks) as long as these faults are independent of one another. Yet, targeted attacks on the timing behavior of tasks which utilize information gained about the system behavior violate the fault independence assumption fault tolerance is based on. This violation may give attackers the opportunity to compromise all replicas simultaneously, in par- ticular if they can mount the attack from already compromised components. In this paper, we ana- lyze vulnerabilities of time-triggered systems, focusing on safety-certified multicore real-time systems. We introduce two runtime mitigation strategies to withstand directed timing inference based attacks: (i) schedule randomization at slot level, and (ii) randomization within a set of offline constructed schedules. We evaluate these mitigation strategies with synthetic experiments and a real case study to show their effectiveness and practicality. [less ▲]

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See detailLe droit international antiesclavagiste des "nations civilisées" (1815-1945)
Erpelding, Michel UL

Book published by Institut Universitaire Varenne/LGDJ (2017)

The prohibition of slavery is a fundamental norm in contemporary international law. It is an integral part of all major human rights instruments, and it is generally presented as an obligation towards the ... [more ▼]

The prohibition of slavery is a fundamental norm in contemporary international law. It is an integral part of all major human rights instruments, and it is generally presented as an obligation towards the international community as a whole. Prior to the Second World War and the emergence of international human rights, the international antislavery law was tightly linked to the ambiguous idea of “civilisation” and, more precisely, to the ability of the Western States to define themselves as “civilised nations” as compared to the rest of the world. As a matter of fact, the very notion of “civilised nations” appeared for the first time in the history of international law in the Declaration of the Eight Courts Relative to the Universal Abolition of the Slave Trade of 8 February 1815. Signed at the Congress of Vienna, the Declaration was also the first multilateral instrument that condemned the slave trade. As shown through the book’s systematic survey of relevant State practice (including more than 450 slavery-related treaties and numerous pieces of colonial legislation relating to slavery and forced labour), the antislavery principle proclaimed in 1815 soon gave rise to more stringent and detailed norms. However, its precise scope remained under constant debate. One major question that arose during these debates was whether a “civilised nation” which had formally abolished the institution of slavery but tolerated or used certain forms of forced labour could be accused of having infringed its obligations under international antislavery law. Only in 1945 would the adoption of the Nuremberg Charter bring a positive answer to that question. In short: - First systematic comparative study of slavery and forced labour in international and colonial law before the advent of international human rights - First systematic survey of hundreds of antislavery treaties (including several hundred treaties with non-Western polities). [less ▲]

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See detailL'esclavage en droit international : aux origines de la relecture actuelle de la définition conventionnelle de 1926
Erpelding, Michel UL

in Journal of the History of International Law (2015), 17(2), 170-220

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