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See detailL'archive sera dédiée ou ne sera pas
Schafer, Valerie UL

Presentation (2020, January 23)

Intervention dans le cadre de la thématique Avenir de l'archive sur IA, archives et place des archivistes, bibliothécaires et documentalistes dans ces évolutions.

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See detailSchool-Class Co-Ethnic and Immigrant Density and Current Smoking among Immigrant Adolescents
Kern, Matthias Robert UL; Heinz, Andreas UL; Willems, Helmut UL

in International Journal of Environmental Research and Public Health (2020), 17(2),

Although the school-class is known to be an important setting for adolescent risk behavior, little is known about how the ethnic composition of a school-class impacts substance use among pupils with a ... [more ▼]

Although the school-class is known to be an important setting for adolescent risk behavior, little is known about how the ethnic composition of a school-class impacts substance use among pupils with a migration background. Moreover, the few existing studies do not distinguish between co-ethnic density (i.e., the share of immigrants belonging to one’s own ethnic group) and immigrant density (the share of all immigrants). This is all the more surprising since a high co-ethnic density can be expected to protect against substance use by increasing levels of social support and decreasing acculturative stress, whereas a high immigrant density can be expected to do the opposite by facilitating inter-ethnic conflict and identity threat. This study analyses how co-ethnic density and immigrant density are correlated with smoking among pupils of Portuguese origin in Luxembourg. A multi-level analysis is used to analyze data from the Luxembourg Health Behavior in School-Aged Children study (N = 4268 pupils from 283 classes). High levels of co-ethnic density reduced current smoking. In contrast, high levels of immigrant density increased it. Thus, in research on the health of migrants, the distinction between co-ethnic density and immigrant density should be taken into account, as both may have opposite effects. [less ▲]

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See detailSexual abuse of adolescents - methodological problems of victimisation surveys
Heinz, Andreas UL

Presentation (2020, January 15)

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See detailComputers and Computing in Society
Schafer, Valerie UL

in NTM (2020)

This review essay aims to highlight some of these recent trends within the history of computing and information technology through the consideration of three recently published books : 1/ Frank Bösch (Ed ... [more ▼]

This review essay aims to highlight some of these recent trends within the history of computing and information technology through the consideration of three recently published books : 1/ Frank Bösch (Ed.) 2018. Wege in die Gesellschaft. Computernutzung in der Bundesrepublik (1955–1990). Geschichte der Gegenwart, Bd. 20. Göttingen: Wallstein, geb.; 2/ Marie Hicks 2017. Programmed Inequality. How Britain Discarded Women Technologists and Lost Its Edge in Computing. Cambridge, MA: MIT Press; 3/ Joy Lisi Rankin 2018. A People’s History of Computing in the United States. Cambridge, MA: Harvard University Press. They are increasingly opening up to approaches that are oriented towards society and actors, whether the latter are producers, regulators, users, or even maintainers. This is achieved with historical rigour by the authors, who highlight the history of a field that is not only scientific, technical, industrial and economic, but also profoundly social, and which is marked by multiple debates, negotiations and power relationships. [less ▲]

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See detailMobility policy through the lens of policy mobility: The post-political case of introducing free transit in Luxembourg
Carr, Constance UL; Hesse, Markus UL

in Journal of Transport Geography (2020), 83

This viewpoint paper addresses the issue of fare-free public transport (FFPT) in the context of policy mobility, the strand of urban studies literature that examines how policy formulations developed in ... [more ▼]

This viewpoint paper addresses the issue of fare-free public transport (FFPT) in the context of policy mobility, the strand of urban studies literature that examines how policy formulations developed in one place tend to ‘travel’ and inform and inspire plans elsewhere as good or best practices. We argue that the promotion of policies may not reflect a serious attempt to solve a sustainability or socio-economic issue. Rather, the institutions in charge have different targets in mind. FFPT in Luxembourg is thus more a reflection of a post-political process where politics are severed from the political. [less ▲]

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See detailPerceptions of Society’s Necessary Standard of Living: Are Perceptions Determined by What People Have, or Do They Reflect a Social Consensus?
Gutfleisch, Tamara Rebecca UL; Andreß, Hans-Jürgen

in Social Indicators Research (2020)

Analyses of material deprivation usually use lists of goods and activities to assess an individual’s possessions and to compare it with the society’s standard of living. If the number of possessions falls ... [more ▼]

Analyses of material deprivation usually use lists of goods and activities to assess an individual’s possessions and to compare it with the society’s standard of living. If the number of possessions falls below a certain threshold, the individual is assumed to be materially deprived. Also state-guaranteed minimum income payments are often based on a basket of goods, which are assumed to represent a minimal living standard in the respective society. However, this approach rests on the assumption that a social consensus exists about what constitutes society’s necessary standard of living, which has never been tested in a theoretically and methodologically sound way. Our paper provides a model of the main determinants of standard of living perceptions in the public, develops a measurement model for a survey of necessary items, and tests whether these perceptions are expressions of a consensual normative standard or reflections of the respondent’s idiosyncratic individual living situation. We have used two waves of the GESIS Panel in 2016 to survey the current opinions about the necessary standard of living in the German population. Estimating cross-lagged auto-correlated structural equation models, we find that necessity evaluations are quite homogeneous across social groups but are influenced by individuals’ possessions, which vary within society and hence, challenge the social consensus assumption. Moreover, instead of using only the most necessary items, survey instruments should include both necessary and less necessary items to reflect the whole distribution of possible standard of living perceptions. Our results further suggest that analyses using single items should be avoided due to possible measurement errors. [less ▲]

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See detailLeveraging Privileged Information to Limit Distraction in End-to-End Lane Following
Robinet, François UL; Demeules, Antoine; Frank, Raphaël UL et al

in 2020 IEEE 17th Annual Consumer Communications & Networking Conference (CCNC) (2020)

Convolutional Neural Networks have been successfully used to steer vehicles using only road-facing cameras. In this work, we investigate the use of Privileged Information for training an end-to-end lane ... [more ▼]

Convolutional Neural Networks have been successfully used to steer vehicles using only road-facing cameras. In this work, we investigate the use of Privileged Information for training an end-to-end lane following model. Starting from the prior assumption that such a model should spend a sizeable fraction of its focus on lane markings, we take advantage of lane geometry information available at training time to improve its performance. To this end, we constrain the class of learnable functions by imposing a prior stemming from a lane segmentation task. For each input frame, we compute the set of pixels that most contribute to the prediction of the model using the VisualBackProp method. These pixel-relevance heatmaps are then compared with ground truth lane segmentation masks. A Distraction Loss term is added to the objective to regularize the training process. We learn from real-world data collected using our experimental vehicle and compare the results to those obtained using the simple Mean Squared Error objective. We show that the presence of our regularizer benefits both the performance and the stability of the model across a variety of evaluation metrics. We use a pretrained lane segmentation model without fine-tuning to extract lane marking masks and show that valuable learning signals can be extracted even from imperfect privileged knowledge. This method can be implemented easily and very efficiently on top of an existing architecture, without requiring the addition of any trainable parameter. [less ▲]

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See detailDeep dive into Interledger: Understanding the Interledger ecosystem - Part 4
Trestioreanu, Lucian Andrei UL; Cassagnes, Cyril UL; State, Radu UL

Learning material (2020)

At the technical level, the goal of Interledger is to provide an architecture and a minimal set of protocols to enable interoperability for any value transfer system. The Interledger protocol is literally ... [more ▼]

At the technical level, the goal of Interledger is to provide an architecture and a minimal set of protocols to enable interoperability for any value transfer system. The Interledger protocol is literally a protocol for interledger payments. To understand how is it possible to achieve this goal, several aspects of the technology require a deeper analysis. For this reason, in our journey to become knowledgeable and active contributor we decided to create our own test-bed on our premises. By doing so, we noticed that some aspects are well documented but we found that others might need more attention and clarification. Despite a large community effort, the task to keep information on a fast evolving software ecosystem is tedious and not always the priority for such a project. Therefore, the purpose of this document is to guide, through several hands-on activities, community members who want to engage at different levels. The document consolidates all the relevant information from generating a simple payment to ultimately create a test-bed with the Interledger protocol suite between Ripple and other distributed ledger technology. [less ▲]

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See detailPERFORMANCE EVALUATION AND MODELLING OF SAAS WEB SERVICES IN THE CLOUD
Ibrahim, Abdallah Ali Zainelabden Abdallah UL

Doctoral thesis (2020)

This thesis studies the problem of performance evaluation and assurance of communications and services quality in cloud computing. The cloud computing paradigm has significantly changed the way of doing ... [more ▼]

This thesis studies the problem of performance evaluation and assurance of communications and services quality in cloud computing. The cloud computing paradigm has significantly changed the way of doing business. With cloud computing, companies and end-users can access the vast majority of services online through a virtualized environment. The main three services typically consumed by cloud users are Infrastructure-as-a-Service (IaaS), Platform-as-a-Service (PaaS) and Software-as-a-Service (SaaS). Cloud Services Providers (CSPs) deliver cloud services to cloud customers on a pay-per-use model while the quality of the provided services is defined using Service Level Agreements (SLAs). Unfortunately, there is no standard mechanism which exists to verify and assure that delivered services satisfy the signed SLA agreement in an automatic way, which impedes the possibility to measure accurately the Quality of Service (QoS). In this context, this thesis aims at offering an automatic framework to evaluate the QoS and SLA compliance of Web Services (WSs) offered across several CSPs. Yet unlike other approaches, the framework aims at quantifying in a fair and by stealth way the performance and scalability of the delivered WS. By stealthiness, it refers to the capacity of evaluating a given Cloud service through multiple workload patterns that makes them indistinguishable from regular user traffic from the provider point of view. This thesis work is motivated by recent scandals in the automotive sector, which demonstrate the capacity of solution providers to adapt to the behavior of their product when submitted to an evaluation campaign to improve the performance results. The framework defines a set of Common performance metrics handled by a set of agents within customized clients for measuring the behavior of cloud applications on top of a given CSP. Once modeled accurately, the agent behavior can be dynamically adapted to hide the true nature of the framework client to the CSP. In particular, the following contributions are proposed: • A new framework of performance metrics for communication systems of cloud computing SaaS. The proposed framework evaluates and classifies in a fair and stealth way the performance and scalability of the delivered WS across multiple CSPs. • Analysis of the performance metrics for the cloud SaaS Web Service (WS) by analyzing all the possible metrics which could be used to evaluate and monitor the behavior of the cloud applications. • Benchmarking the cloud SaaS applications and web services by using referenced benchmarking tools and frameworks. • Modeling the SaaS WS by providing a set of Gaussian models. These models can be used to help the other researchers to generate data representing the CSP’s behavior under a high load and under the normal usage in just a couple of minutes without any experiments. • A novel optimization model to obfuscate the testing from the CSP and to achieve stealthiness. The optimization process relies on meta-heuristic and machine learning algorithms, such as Genetic Algorithm and Gaussian Process Regression accordingly. • A virtual QoS aggregator and SLA checker which takes care of evaluating the QoS and SLA compliance of the WS offered across the considered CSPs. • Ranking multiple CSPs based on multi-criteria decision analysis. [less ▲]

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See detailThe ALMA-Yactul Ecosystem: A Holistic Approach for Student-centered Integration of Learning Material
Grevisse, Christian UL

Doctoral thesis (2020)

Digital learning resources play a key role in technology enhanced learning, yet their organization poses a challenge to both learners and teachers. Students are confronted with an ever-growing amount of ... [more ▼]

Digital learning resources play a key role in technology enhanced learning, yet their organization poses a challenge to both learners and teachers. Students are confronted with an ever-growing amount of available resources in an open, heterogeneous corpus. Finding relevant learning material for a given context or task, such as an exercise, is non-trivial, especially for novices in a complex domain, who often lack specific search skills. In addition, there is often no direct link between the learning material and the task at hand, and the constant interruption of the task in order to search for resources may have an impact on the cognitive load. Moreover, from the perspective of teachers and instructional designers, authoring high-quality learning material is a time-intensive task. Hence, reusing the authored material in multiple contexts would be beneficial. This dissertation addresses these issues by proposing the ALMA-Yactul ecosystem, a holistic approach for student-centered integration of learning material. Learners can benefit from scaffolding support to retrieve learning material relevant to their current context at a fine-grained level and across the boundaries of individual courses. This integration is showcased in multiple applications and domains, such as a plugin for an Integrated Development Environment or an enhanced sketchnoting app. While the former provides novices in computer programming the necessary tools to scaffold the search for heterogeneous documents on fine-grained syntactical elements, the latter allows for suggesting further information while taking notes in class. In both cases, it is not necessary for learners to leave their current study environment. To implicitly link learning resources and tasks, Semantic Web technologies such as ontologies are used to annotate documents. For this purpose, an extensible and lightweight modular domain ontology for programming languages has been created. While the main study domain in this work is computer science with a special focus on programming, the transferability of the proposed approach to other domains is demonstrated through multiple examples. Furthermore, to foster the active engagement of students in the learning process, Yactul, a game-based platform for continuous active learning has been developed. Apart from its use in the classroom, the platform also provides formative assessment to the individual learner by keeping track of her performance on a per-concept basis. Yactul activities are a key element in the ecosystem, both benefitting from and contributing to the integration of learning material. Finally, teachers are assisted in semantically enhancing their resources through semi-automatic annotation support within popular authoring tools. A Knowledge Graph-based approach is employed for core concept identification. Apart from analysing the usage of this ecosystem and evaluating the user satisfaction in university courses, an experiment with high school pupils lacking prior knowledge in programming yielded positive results with respect to the proposed scaffolding support. [less ▲]

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See detailThe Schwarz-Voronov embedding of Z_2^n - manifolds
Bruce, Andrew UL; Ibarguengoytia, Eduardo UL; Poncin, Norbert UL

in Symmetry, Integrability and Geometry: Methods and Applications (2020), 16(002), 47

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See detailBlockPGP: A Blockchain-based Framework for PGP Key Servers
Yakubov, Alexander UL; Shbair, Wazen UL; Khan, Nida UL et al

in International Journal of Networking and Computing (2020), 10(1), 1-24

Pretty Good Privacy (PGP) is one of the most prominent cryptographic standards offering end-to-end encryption for email messages and other sensitive information exchange. PGP allows to verify the identity ... [more ▼]

Pretty Good Privacy (PGP) is one of the most prominent cryptographic standards offering end-to-end encryption for email messages and other sensitive information exchange. PGP allows to verify the identity of the correspondent in information exchange as well as the information integrity. PGP implements asymmetric encryption with certificates shared through a network of PGP key servers. In this paper, we propose a new PGP management framework with the key servers infrastructure implemented using blockchain technology. Our approach offers fast propagation of certificate revocation among PGP key servers and elimination of man-in-the-middle risks. It also grants users the required access control to update their own PGP certificates, which is not the case with the current PGP key servers. A prototype has been implemented using Ethereum blockchain and an open source key server, named Hockeypuck. Finally, we evaluated the prototype with extensive experiments. Our results show that our solution is practical and it could be integrated with the existing public PGP key servers infrastructure. [less ▲]

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See detailCognitive Factors associated to Gaming Disorders
Billieux, Joël; Potenza, Marc; Maurage, Pierre et al

in Verdejo-Garcia, Antonio (Ed.) Cognition and addiction: A Researcher’s Guide From Mechanisms Towards Interventions (2020)

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See detailA newform theory for Katz modular forms
Berhanu, Daniel UL

E-print/Working paper (2020)

In this paper, a strong multiplicity one theorem for Katz modular forms is studied. We show that a cuspidal Katz eigenform which admits an irreducible Galois representation is in the level and weight old ... [more ▼]

In this paper, a strong multiplicity one theorem for Katz modular forms is studied. We show that a cuspidal Katz eigenform which admits an irreducible Galois representation is in the level and weight old space of a uniquely associated Katz newform. We also set up multiplicity one results for Katz eigenforms which have reducible Galois representation. [less ▲]

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See detailDie Landwirtschaft in der Provinz Gallia Narbonensis und die Frage nach dem Sozialstatus der Arbeitskräfte
Groff, Thierry UL

in Frankfurter elektronische Rundschau zur Altertumskunde (2020), 39(2019), 1-12

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See detailMagnetic Guinier law
Michels, Andreas UL; Malyeyev, Artem UL; Titov, Ivan UL et al

in IUCrJ (2020), 7

Small-angle scattering of x-rays and neutrons is a routine method for the determination of nanoparticle sizes. The so-called Guinier law represents the low-q approximation for the small-angle scattering ... [more ▼]

Small-angle scattering of x-rays and neutrons is a routine method for the determination of nanoparticle sizes. The so-called Guinier law represents the low-q approximation for the small-angle scattering curve from an assembly of particles. The Guinier law has originally been derived for nonmagnetic particle-matrix-type systems, and it is successfully employed for the estimation of particle sizes in various scientific domains (e.g., soft matter physics, biology, colloidal chemistry, materials science). An important prerequisite for it to apply is the presence of a discontinuous interface separating particles and matrix. Here, we introduce the Guinier law for the case of magnetic small-angle neutron scattering (SANS) and experimentally demonstrate its applicability for the example of nanocrystalline cobalt. It is well- known that the magnetic microstructure of nanocrystalline ferromagnets is highly nonuniform on the nanometer length scale and characterized by a spectrum of continuously varying long-wavelength magnetization fluctuations, i.e., these systems do not manifest sharp interfaces in their magnetization profile. The magnetic Guinier radius depends on the applied magnetic field, on the magnetic interactions (exchange, magnetostatics), and on the magnetic anisotropy-field radius, which characterizes the size over which the magnetic anisotropy field is coherently aligned into the same direction. In contrast to the nonmagnetic conventional Guinier law, the magnetic version can be applied to fully dense random-anisotropy-type ferromagnets. [less ▲]

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See detailHybrid Analog-Digital Transceiver Designs for Multi-User MIMO mmWave Cognitive Radio Systems
Tsinos, Christos UL; Chatzinotas, Symeon UL; Ottersten, Björn UL

in IEEE Transactions on Cognitive Communications and Networking (2020)

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