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See detailThe promise of solution-processed Fe2GeS4 thin films in iron chalcogenide photovoltaics
Liu, Mimi; Berg, Dominik M.; Hwang, Po-Yu et al

in Journal of Materials Science (2018)

The olivine Fe2GeS4, featuring non-toxic elements, cost-effective synthesis, and suitable optoelectronic properties, recently emerged as a promising light-absorbing candidate. Fe2GeS4 precursor powders ... [more ▼]

The olivine Fe2GeS4, featuring non-toxic elements, cost-effective synthesis, and suitable optoelectronic properties, recently emerged as a promising light-absorbing candidate. Fe2GeS4 precursor powders obtained via a simple solutionbased process were converted to highly crystalline Fe2GeS4 powders upon a thermal treatment in controlled atmosphere. Thin films fabricated by dip coating in the Fe2GeS4 precursor dispersion and subjected to the same thermal treatment render high-purity Fe2GeS4 thin films with a band gap of 1.4 eV, measured by room-temperature photoluminescence. Using Fe2GeS4 thin films as the sole absorber in a solution-based solar cell, open-circuit voltages of 361 mV are observed, while the use of the Fe2GeS4 films as counter electrodes in dyesensitized solar cell constructs enhances the overall power conversion efficiency of the cell by a factor of five. This is the first report of a photovoltaic device based on Fe2GeS4. [less ▲]

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See detailLe patrimoine industriel: Objet de nostalgie ou sujet de recherche?
Scuto, Denis UL

Speeches/Talks (2018)

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See detailThe value of education among immigrants and non-immigrants and how this translates into educational aspirations: a comparison of four European countries
Hadjar, Andreas UL; Scharf, Jan UL

in Journal of Ethnic and Migration Studies (2018), early online

Starting out from the frequent empirical finding that immigrants exhibit higher educational aspirations than non-immigrants, we analyse the role of immigrants’ value of education, i.e. the subjective ... [more ▼]

Starting out from the frequent empirical finding that immigrants exhibit higher educational aspirations than non-immigrants, we analyse the role of immigrants’ value of education, i.e. the subjective belief that education is beneficial for one’s life, in idealistic and realistic educational aspirations in four distinct institutional settings, comparing Sweden, Germany, the Netherlands and England. While the first part of the analyses relates to how immigrants differ from non-immigrants in the value they assign to education, the second part centres on country differences considering immigrant integration policies and education systems as crucial factors. A third part relates to the links between the value of education and educational aspirations to gain some insight into how the value of education may contribute to educational decisions. Analyses are based on longitudinal data of the Children of Immigrants Longitudinal Survey in Four European Countries (CILS4EU). While results show that immigrants assign a higher value to education, the value of education does play a minor role in idealistic and realistic educational aspirations. The results of the country comparison are rather ambivalent, including very weak support for the argument that immigrants strive for education to a higher extent in countries with less favourable conditions. [less ▲]

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See detailMicrofluidic Tensiometry Technique for the Characterization of the Interfacial Tension between Immiscible Liquids.
Honaker, Lawrence William UL; Lagerwall, Jan UL; Jampani, Venkata UL

in Langmuir (2018)

The interfacial tension between two immiscible fluids is of critical importance for understanding many natural phenomena as well as in industrial production processes; however, it can be challenging to ... [more ▼]

The interfacial tension between two immiscible fluids is of critical importance for understanding many natural phenomena as well as in industrial production processes; however, it can be challenging to measure this parameter with high accuracy. Most commonly used techniques have significant shortcomings because of their reliance on other data such as density or viscosity. To overcome these issues, we devise a technique that works with very small sample quantities and does not require any data about either fluid, based on micropipette aspiration techniques. The method facilitates the generation of a droplet of one fluid inside of the other, followed by immediate in situ aspiration of the droplet into a constricted channel. A modified Young-Laplace equation is then used to relate the pressure needed to produce a given deformation of the droplet's radius to the interfacial tension. We demonstrate this technique on different systems with interfacial tensions ranging from sub-millinewton per meter to several hundred millinewton per meter, thus over 4 orders of magnitude, obtaining precise results in agreement with the literature solely from experimental observations of the droplet deformation. [less ▲]

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See detailConservation Laws Shape Dissipation
Rao, Riccardo UL; Esposito, Massimiliano UL

in New Journal of Physics (2018), 20

Starting from the most general formulation of stochastic thermodynamics—i.e. a thermodynamically consistent nonautonomous stochastic dynamics describing systems in contact with several reservoirs —we ... [more ▼]

Starting from the most general formulation of stochastic thermodynamics—i.e. a thermodynamically consistent nonautonomous stochastic dynamics describing systems in contact with several reservoirs —we define a procedure to identify the conservative and the minimal set of nonconservative contributions in the entropy production. The former is expressed as the difference between changes caused by time-dependent drivings and a generalized potential difference. The latter is a sum over the minimal set of flux-force contributions controlling the dissipative flows across the system. When the system is initially prepared at equilibrium (e.g. by turning off drivings and forces), a finite-time detailed fluctuation theorem holds for the different contributions. Our approach relies on identifying the complete set of conserved quantities and can be viewed as the extension of the theory of generalized Gibbs ensembles to nonequilibrium situations. [less ▲]

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See detailLe Carnaval – du Bassin minier au Brésil minier
Santana, Dominique UL

Article for general public (2018)

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See detailSimulation-Based Fault Injection as a Verification Oracle for the Engineering of Time-Triggered Ethernet networks
Fejoz, Loïc; Regnier, Bruno; Miramont, Philippe et al

Scientific Conference (2018, February 02)

TTEthernet (TTE) is considered for use as high-speed backbone in the avionics of next-generation orbital space launchers. Given the key role of communication in launchers, the OEM must acquire a precise ... [more ▼]

TTEthernet (TTE) is considered for use as high-speed backbone in the avionics of next-generation orbital space launchers. Given the key role of communication in launchers, the OEM must acquire a precise understanding of TTE’s functioning and its performances in nominal and error conditions. This holds especially true for the clock synchronization algorithm, the cornerstone of time-triggered communication in TTE, which involves complex distributed algorithms. In this study, we use both an experimental platform and fault-injection on a simulation model to gain quantified insights in these questions. We first describe a fine-grained simulation model of TTE model and discuss how it has been validated against communication traces recorded on the TTE platform. We then present experiments that evaluate the accuracy of the clock synchronization in TTE in the fault-free case as well as considering permanent link failure and transient transmission errors. Finally, we discuss what we have learned during the project in terms of development process and programming language support for complex simulation models used in the design of critical systems. [less ▲]

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See detailInsights on the Performance and Configuration of AVB and TSN in Automotive Ethernet Networks
Migge, Jörn; Villanueva, Josetxo; Navet, Nicolas UL et al

Scientific Conference (2018, February 02)

Switched Ethernet is profoundly reshaping in-car communications. To meet the diverse real-time requirements in automotive communications, Quality-of-Service protocols that go beyond the mere use of ... [more ▼]

Switched Ethernet is profoundly reshaping in-car communications. To meet the diverse real-time requirements in automotive communications, Quality-of-Service protocols that go beyond the mere use of priorities are required. In this work, the basic questions that we investigate on a case-study with diverse and demanding communication requirements is what can we expect from the various protocols aimed at providing a better timing Quality of Service on top of Ethernet? And how to use them? Especially how to use them in a combined manner. We will focus on the Credit-Based Shaper of AVB, the Time-Aware Shaper of TSN and the use of priorities as defined in IEEE802.1Q. The performance metrics considered are the distributions of the communication latencies, obtained by simulation, as well as upper bounds on these quantities obtained by worst-case schedulability analysis. If there have been over the last 5 years numerous studies on the performance of AVB CBS, the literature on comparing AVB to TSN and other candidate protocols is still sparse. To the best of our knowledge, this empirical study is the first to consider most protocols currently considered in the automotive domain, with the aim to gain insights into the different technological, design and configurations alternatives. In particular, an objective of this study is to identify key problems that need to be solved in order to further automate network design and configuration. [less ▲]

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See detailIdentification and Characterization of Variant Intolerant Sites across Human Protein 3-Dimensional Structures
Iqbal, Sumaiya; Berg Jespersen, Jakob; Perez-Palma, Eduardo et al

in Biophysical Journal (2018, February 02), 114(3, Suppl. 1), 664

The functional interpretation of genetic variation in disease-associated genes is far outpaced by data generation. Existing algorithms for prediction of variant consequences do not adequately distinguish ... [more ▼]

The functional interpretation of genetic variation in disease-associated genes is far outpaced by data generation. Existing algorithms for prediction of variant consequences do not adequately distinguish pathogenic variants from benign rare variants. This lack of statistical and bioinformatics analyses, accompanied by an ever-increasing number of identified variants in biomedical research and clinical applications, has become a major challenge. Established methods to predict the functional effect of genetic variation use the degree of amino acid conservation across species in linear protein sequence alignment. More recent methods include the spatial distribution pattern of known patient and control variants. Here, we propose to combine the linear conservation and spatial constrained based scores to devise a novel score that incorporates 3-dimensional structural properties of amino acid residues, such as the solvent-accessible surface area, degree of flexibility, secondary structure propensity and binding tendency, to quantify the effect of amino acid substitutions. For this study, we develop a framework for large-scale mapping of established linear sequence-based paralog and ortholog conservation scores onto the tertiary structures of human proteins. This framework can be utilized to map the spatial distribution of mutations on solved protein structures as well as homology models. As a proof of concept, using a homology model of the human Nav1.2 voltage-gated sodium channel structure, we observe spatial clustering in distinct domains of mutations, associated with Autism Spectrum Disorder (>20 variants) and Epilepsy (>100 variants), that exert opposing effects on channel function. We are currently characterizing all variants (>300k individuals) found in ClinVar, the largest disease variant database, as well as variants identified in >140k individuals from general population. The variant mapping framework and our score, informed with structural information, will be useful in identifying structural motifs of proteins associated with disease risk. [less ▲]

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See detailWho Decides What? Judicial Deference in International Economic Adjudication
Fahner, Johannes Hendrik UL

Presentation (2018, February 01)

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See detailReligionsunterricht in Luxemburg aus diskurstheoretischer Sicht: eine spannende Geschichte und eine spannungsvolle Zukunft
Weber, Jean-Marie UL

in Jean, Ehret; Zeien, Jean-Louis (Eds.) Herausforderung Religion(en) und Schule(n) (2018)

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See detailLimit theorems for symmetric U-statistics using contractions
Döbler, Christian UL; Peccati, Giovanni UL

E-print/Working paper (2018)

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See detailEnergy efficiency optimization in MIMO interference channels: A successive pseudoconvex approximation approach
Yang, Yang UL; Pesavento, Marius; Chatzinotas, Symeon UL et al

E-print/Working paper (2018)

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See detailWas wissen wir über die Osteitis pubis bei Sporttreibenden?
Kelm, Jens; Ludwig, Oliver; André, Jan et al

in Sportverletzung Sportschaden : Organ der Gesellschaft für Orthopadisch-Traumatologische Sportmedizin (2018)

Hintergrund Die Osteitis pubis ist eine häufige Ursache chronischer Leistenbeschwerden. Aufgrund hoher klinischer Unsicherheit sowie dem unterschiedlichen Verlauf der Erkrankung wird die Diagnose nicht ... [more ▼]

Hintergrund Die Osteitis pubis ist eine häufige Ursache chronischer Leistenbeschwerden. Aufgrund hoher klinischer Unsicherheit sowie dem unterschiedlichen Verlauf der Erkrankung wird die Diagnose nicht selten erst spät gestellt. Das Krankheitsbild betrifft insbesondere Sportlerinnen und Sportler, wobei auch Patienten aus den Bereichen Orthopädie, Traumatologie, Neurologie, Urologie, Gynäkologie sowie der Rheumatologie betroffen sein können. Therapeutisch kommen sowohl konservative als auch operative Verfahren zum Einsatz. Material und Methoden Systematische Literaturrecherche, deskriptive Darstellung der Studienlage und Interpretation der Ergebnisse im Sinne der evidenzbasierten Medizin. Ergebnisse Das wissenschaftliche Niveau der Studien über die Osteitis pubis ist, wie die Anzahl der in Studien inkludierten Sporttreibenden, insgesamt niedrig. Aufgrund der Heterogenität der Publikationen ist ihr statistischer Vergleich methodisch schwierig. Klinisch führendes Symptom der Osteitis pubis ist die schmerzhafte Symphysis pubica, wobei ein klassisches pathognomonisches Zeichen fehlt. Die Diagnose basiert nach Ausschluss zahlreicher Differentialdiagnosen (z. B. „Sportlerleiste“, FA-Impingement, Adduktorenläsion) auf der Zusammenschau von Anamnese, klinischer Untersuchung sowie bildgebender Verfahren. Die Osteitis pubis ist eine durch Sportkarenz oftmals selbstlimitierende Erkrankung, die initial konservativ behandelt wird. Bei frustranem Verlauf sind operative Verfahren, in Abhängigkeit der Begleitpathologien, in Betracht zu ziehen. Schlussfolgerung Es existieren bis dato keine Leitlinien hinsichtlich Diagnostik und Therapie der Osteitis pubis, allerdings ein Konsens darüber, dass der operativen Behandlung eine konservative vorangehen muss. Das Evidenzniveau der Studien ist niedrig. Eine metaanalytische Auswertung ist mit den derzeitig vorhandenen Publikationen nicht möglich. Die Anzahl der untersuchten Sporttreibenden ist in Relation zu den sozioökonomischen Folgen der Erkrankung, insbesondere im Profisport, niedrig. [less ▲]

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See detailMultiple crack detection in 3D using a stable XFEM and global optimization
Agathos, Konstantinos; Chatzi, Eleni; Bordas, Stéphane UL

in Computational Mechanics (2018)

A numerical scheme is proposed for the detection of multiple cracks in three dimensional (3D) structures. The scheme is based on a variant of the extended finite element method (XFEM) and a hybrid ... [more ▼]

A numerical scheme is proposed for the detection of multiple cracks in three dimensional (3D) structures. The scheme is based on a variant of the extended finite element method (XFEM) and a hybrid optimizer solution. The proposed XFEM variant is particularly well-suited for the simulation of 3D fracture problems, and as such serves as an efficient solution to the so-called forward problem. A set of heuristic optimization algorithms are recombined into a multiscale optimization scheme. The introduced approach proves effective in tackling the complex inverse problem involved, where identification of multiple flaws is sought on the basis of sparse measurements collected near the structural boundary. The potential of the scheme is demonstrated through a set of numerical case studies of varying complexity. [less ▲]

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See detailEdge-Caching Wireless Networks: Performance Analysis and Optimization
Vu, Thang Xuan UL; Chatzinotas, Symeon UL; Ottersten, Björn UL

in IEEE Transactions on Wireless Communications (2018)

Edge-caching has received much attention as an efficient technique to reduce delivery latency and network congestion during peak-traffic times by bringing data closer to end users. Existing works usually ... [more ▼]

Edge-caching has received much attention as an efficient technique to reduce delivery latency and network congestion during peak-traffic times by bringing data closer to end users. Existing works usually design caching algorithms separately from physical layer design. In this paper, we analyse edge-caching wireless networks by taking into account the caching capability when designing the signal transmission. Particularly, we investigate multi-layer caching where both base station (BS) and users are capable of storing content data in their local cache and analyse the performance of edge-caching wireless networks under two notable uncoded and coded caching strategies. Firstly, we calculate backhaul and access throughputs of the two caching strategies for arbitrary values of cache size. The required backhaul and access throughputs are derived as a function of the BS and user cache sizes. Secondly, closed-form expressions for the system energy efficiency (EE) corresponding to the two caching methods are derived. Based on the derived formulas, the system EE is maximized via precoding vectors design and optimization while satisfying a predefined user request rate. Thirdly, two optimization problems are proposed to minimize the content delivery time for the two caching strategies. Finally, numerical results are presented to verify the effectiveness of the two caching methods. [less ▲]

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See detailOn the effect of grains interface parameters on the macroscopic properties of polycrystalline materials
Akbari, Ahmad; Kerfriden, Pierre; Bordas, Stéphane UL

in Computers & Structures (2018), 196

In this paper, the influence of microscopic parameters on the macroscopic behaviour of polycrystalline materials under different loading configuration is investigated. Linear elastic grains with zero ... [more ▼]

In this paper, the influence of microscopic parameters on the macroscopic behaviour of polycrystalline materials under different loading configuration is investigated. Linear elastic grains with zero thickness cohesive interfaces are considered at the microscale with in depth introduction of effective parameters. A multiscale method based on homogenisation technique is employed to bridge the scales. In order to minimize the homogenisation error, a representative volume element (RVE) of the microscopic structure is statistically determined to be used in the numerical analysis. For each loading condition of the RVE, several numerical examinations are conducted to illustrate the relationship between the microscopic parameters. Finally, the effects of microscopic critical fracture energies, maximum tensile and shear strengths of grain interfaces on the mechanical properties, i.e. stress-strain curve and yield surface at the macroscale are discussed in details. It is shown that macroscopic yield surface and stress strain curves can be used to characterise the microscopic properties. [less ▲]

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See detailMixed stereotype content and attitudes toward students with special educational needs and their inclusion in regular schools in Luxembourg
Krischler, Mireille UL; Pit-Ten Cate, Ineke UL; Krolak-Schwerdt, Sabine UL

in Research in Developmental Disabilities (2018), 75

Background: Students with special educational needs (SEN) remain one of the most socially excluded and vulnerable groups. To this extent, negative attitudes and stereotypes may impede their inclusion ... [more ▼]

Background: Students with special educational needs (SEN) remain one of the most socially excluded and vulnerable groups. To this extent, negative attitudes and stereotypes may impede their inclusion. Theoretical frameworks have suggested that stereotypes and attitudes elicit differential expectations and judgments, which in turn affect (social) behaviors. Aims: In this study, we aimed to investigate the stereotypes and implicit attitudes held by a sample of Luxemburgish adults toward students with learning difficulties and challenging behavior. We also explored the adults’ explicit attitudes towards inclusion. Method and procedures: Participants (N=103) completed an evaluative priming task and rated students on the stereotype dimensions of warmth and competence. In addition, they completed the German version of The Opinions Relative to Integration of Students with Disabilities questionnaire and provided demographic information. Outcomes and results: Results showed differential stereotype content with respect to students with learning difficulties and challenging behavior. Results further indicated that participants’ implicit attitudes toward both challenging behavior and learning difficulties were negative. By contrast, participants expressed positive attitudes towards inclusion. Conclusions and implications: The results of the current study contribute to the understanding of why some people accept, whereas others reject students with SEN. Understanding prevalent stereotypes and attitudes can inform the development of targeted interventions to promote and facilitate the social inclusion of students with SEN. [less ▲]

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