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See detailCoupled CFD-DEM with Heat and Mass transfer to Investigate the Melting of a Granular Packed Bed
Baniasadi, Mehdi UL; Baniasadi, Maryam UL; Peters, Bernhard UL

in Chemical Engineering Science (2017)

The eXtended Discrete Element Method (XDEM) platform which is a Coupled Eulerian-Lagrangian framework with heat and mass transfer, is extended for melting of granular packed beds. In this method, the ... [more ▼]

The eXtended Discrete Element Method (XDEM) platform which is a Coupled Eulerian-Lagrangian framework with heat and mass transfer, is extended for melting of granular packed beds. In this method, the fluid is simulated by computational fluid dynamics (CFD) and the soft-sphere discrete element approach (DEM) is used for the particle system. A four-way coupling accounts for solid-liquid interaction via drag and buoyancy forces and the collisions between the particles and the walls. The contact forces between the particles and wall-particle contacts have been calculated by the hertz-mindlin model. The particles heat up, melt and shrink due to heat and mass exchange, and the temperature distributions inside the particles are described. In order to validate the method, melting of a single ice particle and of a packed bed of ice in flowing water have been carried out. Very good agreement between the simulation and experiment has been achieved. The effects of the temperature and velocity of flowing water on melting rate are also discussed. [less ▲]

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See detailWWII, Russians in Luxembourg: Sowjetesch Zwangsaarbechter zu Lëtzebuerg
Molitor, Maurice; Ganschow, Inna UL

Speeches/Talks (2017)

Am Kader vun engem Recherche-Projet iwwer "100 Joer russesch Emigratioun op Lëtzebuerg" fuerscht d'Inna Ganschow, mat der Ënnerstëtzung vun der Lydie-Schmit-Stëftung, ënnert anerem och iwwer d'Lous vu ... [more ▼]

Am Kader vun engem Recherche-Projet iwwer "100 Joer russesch Emigratioun op Lëtzebuerg" fuerscht d'Inna Ganschow, mat der Ënnerstëtzung vun der Lydie-Schmit-Stëftung, ënnert anerem och iwwer d'Lous vu sowjeteschen Zwangsaarbechter, déi an de Joren 1942 bis 44 op Lëtzebuerger Schmelzen an a Lëtzebuerger Bauerebetriber geschafft hunn. [less ▲]

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See detailWorkshop on Supergeometry and Applications
Bruce, Andrew UL; Poncin, Norbert UL

Report (2017)

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See detailCalculating the Malliavin derivative of some stochastic mechanics problems
Hauseux, Paul UL; Hale, Jack UL; Bordas, Stéphane UL

in PLoS ONE (2017), 12(12), 0189994

The Malliavin calculus is an extension of the classical calculus of variations from deterministic functions to stochastic processes. In this paper we aim to show in a practical and didactic way how to ... [more ▼]

The Malliavin calculus is an extension of the classical calculus of variations from deterministic functions to stochastic processes. In this paper we aim to show in a practical and didactic way how to calculate the Malliavin derivative, the derivative of the expectation of a quantity of interest of a model with respect to its underlying stochastic parameters, for four problems found in mechanics. The non-intrusive approach uses the Malliavin Weight Sampling (MWS) method in conjunction with a standard Monte Carlo method. The models are expressed as ODEs or PDEs and discretised using the finite difference or finite element methods. Specifically, we consider stochastic extensions of; a 1D Kelvin-Voigt viscoelastic model discretised with finite differences, a 1D linear elastic bar, a hyperelastic bar undergoing buckling, and incompressible Navier-Stokes flow around a cylinder, all discretised with finite elements. A further contribution of this paper is an extension of the MWS method to the more difficult case of non-Gaussian random variables and the calculation of second-order derivatives. We provide open-source code for the numerical examples in this paper. [less ▲]

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See detailAn elementary proof of the formal rigidity of the Witt and Virasoro algebra
Schlichenmaier, Martin UL

Scientific Conference (2017, December 19)

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See detailHomotopical Geometry over Differential Operators and Batalin-Vilkovisky Complex
Poncin, Norbert UL

Presentation (2017, December 18)

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See detailModelling argumentation on Axiom of Choice in ASPIC-END -- Technical report
Cramer, Marcos UL

Report (2017)

In this technical report, we present an application of the structured argumentation methodology to a debate in the foundations of mathematics. We work with ASPIC-END, a recently proposed adaptation of the ... [more ▼]

In this technical report, we present an application of the structured argumentation methodology to a debate in the foundations of mathematics. We work with ASPIC-END, a recently proposed adaptation of the structured argumentation framework ASPIC+ which can incorporate debates about logical principles, natural deduction style arguments and explanations. We apply this framework to build a preliminary formal model of parts of the debate that mathematicians had about the Axiom of Choice in the early 20th century. Furthermore, we briefly discuss the insight into the strengths and drawbacks of the modeling capacities of ASPIC-END that we have gained from producing this model. [less ▲]

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See detailHigher Supergeometry Revisited
Poncin, Norbert UL

Presentation (2017, December 14)

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See detailThe publishing process and Open Access
England, Jonathan UL

Presentation (2017, December 13)

Series of workshops tailored towards early-career researchers in Luxembourg explaining the publishing process and how Open Access fits in the traditional journal-subscription based model. The idea is to ... [more ▼]

Series of workshops tailored towards early-career researchers in Luxembourg explaining the publishing process and how Open Access fits in the traditional journal-subscription based model. The idea is to break some of the myths around OA (e.g. OA is a journal, OA is only possible the gold way) by presenting the 'Green' (self-archiving) and 'gold' (paying Article Processing Charges) routes. Some of the benefits are presented, along with the main Luxembourgish funder FNR's mandate. The presentation uploaded was given to PhDs and post-docs from the Luxembourg Institute of Health on 13/12/2017. [less ▲]

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See detailMilitary Migrants. Luxembourgers in the Colonial Army of the Dutch East Indies
Bosma, Ulbe; Kolnberger, Thomas UL

in Itinerario (2017), 41(3), 555-580

Among the roughly 150,000 soldiers sent to the Dutch East Indies between 1815 and 1914, the Luxembourg contingent made up a tiny minority of just 1,075 men. Based upon extensive research into their ... [more ▼]

Among the roughly 150,000 soldiers sent to the Dutch East Indies between 1815 and 1914, the Luxembourg contingent made up a tiny minority of just 1,075 men. Based upon extensive research into their careers, data on these soldiers provide further clues to understanding what drove Europe’s young men to become colonial soldiers. The results of this national case study will be compared with earlier investigations by Bossenbroek and Bosma on recruits for the Dutch colonial army. Similar to the Dutch soldiers, their Luxembourg counterparts had a predominantly urban provenance. However, in contrast to the Dutch, they did not have a strong military background, and it appears that fewer Luxembourgers stayed behind in the Dutch East Indies after their tour of duty. They were more attracted by the payments that the recruiters doled out in advance, particularly at a time of economic crisis, than in a career in the tropics. [less ▲]

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See detailHealth Behaviour in School-aged Children - Studienergebnisse der HBSC-Erhebung 2014
Heinz, Andreas UL

Scientific Conference (2017, December 13)

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See detailResolving the Combinatorial Complexity of Smad Protein Complex Formation and Its Link to Gene Expression.
Lucarelli, Philippe UL; Schilling, Marcel; Kreutz, Clemens et al

in Cell Systems (2017)

Upon stimulation of cells with transforming growth factor beta (TGF-beta), Smad proteins form trimeric complexes and activate a broad spectrum of target genes. It remains unresolved which of the possible ... [more ▼]

Upon stimulation of cells with transforming growth factor beta (TGF-beta), Smad proteins form trimeric complexes and activate a broad spectrum of target genes. It remains unresolved which of the possible Smad complexes are formed in cellular contexts and how these contribute to gene expression. By combining quantitative mass spectrometry with a computational selection strategy, we predict and provide experimental evidence for the three most relevant Smad complexes in the mouse hepatoma cell line Hepa1-6. Utilizing dynamic pathway modeling, we specify the contribution of each Smad complex to the expression of representative Smad target genes, and show that these contributions are conserved in human hepatoma cell lines and primary hepatocytes. We predict, based on gene expression data of patient samples, increased amounts of Smad2/3/4 proteins and Smad2 phosphorylation as hallmarks of hepatocellular carcinoma and experimentally verify this prediction. Our findings demonstrate that modeling approaches can disentangle the complexity of transcription factor complex formation and its impact on gene expression. [less ▲]

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See detailThe Qatar Embargo at the WTO: Finally a Case on Article XXI?
Fahner, Johannes Hendrik UL

Presentation (2017, December 13)

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See detailFirst Vertical Land Movement Estimates on South Georgia Island: An Impact Study on Sea Level Change from Tide Gauge and Altimetry Measurements
Teferle, Felix Norman UL; Hunegnaw, Addisu UL; Abraha, Kibrom Ebuy UL et al

Poster (2017, December 11)

South Georgia Island in the Southern Atlantic Ocean has been a key location for the seismic, geomagnetic and oceanic global monitoring networks. However, no permanent geodetic monitoring station had been ... [more ▼]

South Georgia Island in the Southern Atlantic Ocean has been a key location for the seismic, geomagnetic and oceanic global monitoring networks. However, no permanent geodetic monitoring station had been established there despite the lack of observations from this region within, for example, the International GNSS Service (IGS) network of Global Navigation Satellite System (GNSS) stations. Then, in 2013 the King Edward Point (KEP) Geodetic Observatory was established with a focus on sea level studies and in support of general geoscience applications. Currently, this observatory located roughly half-way along the main island and along its northern coastline, consists of two GNSS stations (KEPA and KRSA) with local benchmark networks, allowing the height determinations from the GNSS antennas to be transferred to the KEP tide gauge (GLOSS ID 187) and forming a height reference within the International Terrestrial Reference Frame. In late 2014, three additional GNSS stations (SG01, SG02 and SG03) were established, all on small islands at the perimeter of the main island. Together the stations provide the best possible opportunity to study various geophysical processes in the region. With the GNSS-derived position time series partly reaching over 4.5 years in length, it has become possible to provide first estimates of vertical land movements for the island and KEP with its surrounding area. Together with four precise levelling campaigns of the benchmark network in 2013, 2014 and two in 2017, it has also been possible to investigate the very local character of the vertical motions, ie. the stability of the jetty upon which the tide gauge is mounted. Our measurements show that while South Georgia Island and the area around KEP are rising, the jetty and tide gauge are subsiding. In this study, we will present the preliminary results from the GNSS and levelling measurements and will discuss their impact on the sea level record from the KEP tide gauge which is ideally situated in a mid-ocean location for satellite altimetry calibration over the Southern Atlantic and Southern Oceans. [less ▲]

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See detailDes hommes ordinaires
Scuto, Denis UL

Article for general public (2017)

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See detailZugangsbarrieren im Gesundheitssystem - Ein Ländervergleich
Heinz, Andreas UL

Scientific Conference (2017, December 08)

In der international vergleichenden Forschung zu Gesundheitssystemen spielt der Zugang zu Gesundheitsleistungen eine zentrale Rolle. Entsprechende Typologien klassifizieren Gesundheitssysteme u.a. danach ... [more ▼]

In der international vergleichenden Forschung zu Gesundheitssystemen spielt der Zugang zu Gesundheitsleistungen eine zentrale Rolle. Entsprechende Typologien klassifizieren Gesundheitssysteme u.a. danach, ob Patienten Zuzahlungen leisten müssen, ob sie sich bei Hausärzten einschreiben müssen und nach welchen Regeln sie einen Facharzt konsultieren können (z.B. Reibling 2010, Wendt 2009, Böhm et al 2013). In der Typologie von Wendt gehört Österreich zum „Health service provision-oriented type“, der fast der gesamten Bevölkerung einen einfachen Zugang zu Gesundheitsleistungen bei geringen Zuzahlungen und freier Arztwahl ermöglicht (2009). Diese Typologien basieren jedoch auf den gesetzlichen Zugangsregeln in einem Land, nicht auf den subjektiven Erfahrungen der Bevölkerung mit Zugangsbarrieren. Im aktuellen European Social Survey (ESS) wurde nach diesen Barrieren gefragt: Haben Befragte medizinische Behandlungen nicht bekommen und was waren die Gründe (z.B. Kosten, Behandlung nicht erhältlich, Warteliste zu lang)? Der Vortrag stellt die Ergebnisse des ESS vor und geht auf folgende Fragen ein: • Wie häufig stoßen Kranke in Österreich und in anderen europäischen Ländern auf Zugangsbarrieren? • Welche Personen in Österreich sind besonders von Zugangsbarrieren betroffen? Die vorläufigen Ergebnisse deuten darauf hin, dass es durchaus nennenswerte Zugangsbarrieren im Gesundheitssystem Österreichs gibt und dass ohnehin benachteiligte Personen häufiger als andere auf Zugangsbarrieren stoßen. Für die wissenschaftliche Theorie stellt sich die Frage, ob die gängigen Typologien von Gesundheitssystemen um die subjektiven Erfahrungen ergänzt werden müssen. Für die Praxis stellt sich die Frage, wie schädlich Zugangsbarrieren sind und wie sie abgebaut werden können. [less ▲]

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See detailStatic and fatigue strength of a novel anatomically contoured implant compared to five current open-wedge high tibial osteotomy plates
Diffo Kaze, Arnaud UL; Maas, Stefan UL; Belsey, James et al

in Journal of Experimental Orthopaedics (2017), 4(39),

Abstract Background The purpose of the present study was to compare the mechanical static and fatigue strength of the size 2 osteotomy plate “Activmotion” with the following five other common implants for ... [more ▼]

Abstract Background The purpose of the present study was to compare the mechanical static and fatigue strength of the size 2 osteotomy plate “Activmotion” with the following five other common implants for the treatment of medial knee joint osteoarthritis: the TomoFix small stature, the TomoFix standard, the Contour Lock, the iBalance and the second generation PEEKPower. Methods Six fourth-generation tibial bone composites underwent a medial open-wedge high tibial osteotomy (HTO), according to standard techniques, using size 2 Activmotion osteotomy plates. All bone-implant constructs were subjected to static compression load to failure and load-controlled cyclic fatigue failure testing, according to a previously defined testing protocol. The mechanical stability was investigated by considering different criteria and parameters: maximum forces, the maximum number of loading cycles, stiffness, the permanent plastic deformation of the specimens during the cyclic fatigue tests, and the maximum displacement range in the hysteresis loops of the cyclic loading responses. Results In each test, all bone-implant constructs with the size 2 Activmotion plate failed with a fracture of the lateral cortex, like with the other five previously tested implants. For the static compression tests the failure occurred in each tested implant above the physiological loading of slow walking (> 2400 N). The load at failure for the Activmotion group was the highest (8200 N). In terms of maximum load and number of cycles performed prior to failure, the size 2 Activmotion plate showed higher results than all the other tested implants except the ContourLock plate. The iBalance implant offered the highest stiffness (3.1 kN/mm) for static loading on the lateral side, while the size 2 Activmotion showed the highest stiffness (4.8 kN/mm) in cyclic loading. Conclusions Overall, regarding all of the analysed strength parameters, the size 2 Activmotion plate provided equivalent or higher mechanical stability compared to the previously tested implant. Implants with a metaphyseal slope adapted to the tibia anatomy, and positioned more anteriorly on the proximal medial side of the tibia, should provide good mechanical stability. [less ▲]

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See detailDiscovery and pathogenicity assessment of neuropathology-associated gene variants
Neupert, Lisa-Marie; May, Patrick UL; Kobow, Katja et al

in Epilepsia (2017, December 08), 58(Suppl.5), 174

Germline and brain-specific somatic variants have been reported as an underlying cause in patients with epilepsy-associated neuropathologies, including focal cortical dysplasias (FCDs) and long-term ... [more ▼]

Germline and brain-specific somatic variants have been reported as an underlying cause in patients with epilepsy-associated neuropathologies, including focal cortical dysplasias (FCDs) and long-term epilepsy associated tumors (LEAT). However, evaluation of identified neuropathology associated variants in genetic screens is complex since not all observed variants contribute to the etiology of neuropathologies not even in genuinely disease-associated genes. Here, we critically reevaluated the pathogenicity of 12 previously published disease-related genes and of 79 neuropathology-associated missense variants listed in the PubMed and ClinVar databases. We (1) assessed the evolutionary gene constraint using the pLI and the missense z score, (2) used the latest American College of Medical Genetics and Genomics (ACMG) guidelines, and (3) performed bioinformatic variant pathogenicity prediction analyses using PolyPhen-2, CADD and GERP. Constraint analysis classified only seven out of 12 genes to be likely disease-associated. Furthermore, 78 (89%) of 88 neuropathology-associated missense variants were classified as being of unknown significance (VUS) and only 10 (11%) as being likely pathogenic (LPII). Pathogenicity prediction yielded a discrimination between LPII variants and a discrimination for VUS compared with rare variant scores from individuals present in the Genome Aggregation Database (gnomAD). In summary, our results demonstrate that interpretation of variants associated with neuropathologies is complex while the application of current ACMG guidelines including bioinformatic pathogenicity prediction can help improving variant evaluation. Furthermore, we will augment this set of literature-identified variants at the conference by results from our variant screen using self-generated deep sequencing data in >150 candidate genes in >50 patients not yet analyzed. [less ▲]

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See detailA finite element model of the lower limb during stance phase of gait cycle including the muscle forces
Diffo Kaze, Arnaud UL; Maas, Stefan UL; Arnoux, Pierre-Jean et al

in BioMedical Engineering OnLine (2017), 16(138),

Abstract Background Results of finite element (FE) analyses can give insight into musculoskeletal diseases if physiological boundary conditions, which include the muscle forces during specific activities ... [more ▼]

Abstract Background Results of finite element (FE) analyses can give insight into musculoskeletal diseases if physiological boundary conditions, which include the muscle forces during specific activities of daily life, are considered in the finite element modelling. So far, many simplifications of the boundary conditions are currently made. This study presents an approach for FE modelling of the lower limb for which muscle forces were included. Method The stance phase of normal gait was simulated. Muscle forces were calculated using a musculoskeletal rigid body (RB) model of the human body, and were subsequently applied to a FE model of the lower limb. It was shown that the inertial forces are negligible during the stance phase of normal gait. The contact surfaces between the parts within the knee were modelled as bonded. Weak springs were attached to the distal tibia for numerical reasons. Results Hip joint reaction forces from the RB model and those from the FE model were similar in magnitude with relative differences less than 16%. The forces of the weak spring were negligible compared to the applied muscle forces. The maximal strain was 0.23% in the proximal region of the femoral diaphysis and 1.7% in the contact zone between the tibia and the fibula. Conclusions The presented approach based on FE modelling by including muscle forces from inverse dynamic analysis of musculoskeletal RB model can be used to perform analyses of the lower limb with very realistic boundary conditions. In the present form, this model can be used to better understand the loading, stresses and strains of bones in the knee area and hence to analyse osteotomy fixation devices. [less ▲]

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