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See detailZoom in den Gerichtssaal? Über das Für und Wider digitaler Gerichtsprozesse
Becker, Katrin UL

Article for general public (2021)

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See detailCoulomb interactions between dipolar quantum fluctuations in van der Waals bound molecules and materials
Stoehr, Martin UL; Sadhukhan, Mainak; Al-Hamdani, Yasmine S. et al

in Nature Communications (2021), 12(1), 137

Mutual Coulomb interactions between electrons lead to a plethora of interesting physical and chemical effects, especially if those interactions involve many fluctuating electrons over large spatial scales ... [more ▼]

Mutual Coulomb interactions between electrons lead to a plethora of interesting physical and chemical effects, especially if those interactions involve many fluctuating electrons over large spatial scales. Here, we identify and study in detail the Coulomb interaction between dipolar quantum fluctuations in the context of van der Waals complexes and materials. Up to now, the interaction arising from the modification of the electron density due to quantum van der Waals interactions was considered to be vanishingly small. We demonstrate that in supramolecular systems and for molecules embedded in nanostructures, such contributions can amount to up to 6 kJ/mol and can even lead to qualitative changes in the long-range van der Waals interaction. Taking into account these broad implications, we advocate for the systematic assessment of so-called Dipole-Correlated Coulomb Singles in large molecular systems and discuss their relevance for explaining several recent puzzling experimental observations of collective behavior in nanostructured materials. [less ▲]

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See detailEVALUATION OF THE JOINT BASED ON DIFFERENT SURFACE CONDITIONS FOR ALUMINUM-POLYAMIDE LASER WELDING
Amne Elahi, Mahdi UL; Koch, Marcus; Plapper, Peter UL

in Journal of Laser Applications (2021)

Laser welding is one of the most promising joining techniques to realize hybrid joints between metals and polymers in order to achieve weight reduction and functionalization of the parts. The surface ... [more ▼]

Laser welding is one of the most promising joining techniques to realize hybrid joints between metals and polymers in order to achieve weight reduction and functionalization of the parts. The surface treatment of the metal has a decisive effect on the joint quality and thus on the mechanical properties. In the present study, different mechanical and laser-based surface treatments have been investigated to develop diverse surface conditions on aluminum. Abrasive blasting and laser ablation were used to increase the surface roughness, while abrasive polishing and laser polishing were applied to minimize the surface roughness. In contrast to abrasive surface treatments, laser-based ones were implemented to create artificial oxide layers on the aluminum surface. The surface structures of pretreated samples have been studied with scanning electron microscopy and roughness test. The laser welding of pretreated aluminum with polyamide was achieved with the heat conduction joining technique. To enlarge the welding area and control the heat input, spatial and temporal modulations of the laser beam were implemented. Finally, a single lap tensile-shear test, microscopic analysis of fractured surfaces, and welding cross sections were employed to evaluate the joints. Results show that the presence of an artificial aluminum oxide layer and low roughness are essential to achieve a superior joint between aluminum and polyamide (improvement of approximately 58% in the shear load of the joint compared to as-received welded samples). The cross section of the superior joint which is the laser-polished aluminum welded to polyamide is studied with transmission electron microscopy. [less ▲]

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See detailStrain effects on band structure and Dirac nodal-line morphology of ZrSiSe
Bernardus, Rendy; Hasdeo, Eddwi Hesky UL

in Journal of Applied Physics (2021), 129(1), 014306

The Dirac nodal-line semimetals are new promising materials for technological applications due to their exotic properties, which originate from band structure dispersion and nodal-line behavior. We report ... [more ▼]

The Dirac nodal-line semimetals are new promising materials for technological applications due to their exotic properties, which originate from band structure dispersion and nodal-line behavior. We report strain effects on the band structure of ZrSiSe Dirac nodal-line semimetal through the density functional theory calculations. We found that the kz=0 Dirac nodal-line of ZrSiSe is robust to all strains under reasonable magnitude although there are significant changes in the band oscillation amplitude, bandgap, and band occupancy due to orbital interactions and the Fermi energy shift upon strains. We also found that the effective strains to tune the nodal-line and band structure are equi-biaxial tensile, uniaxial (100) tensile, and xz-plane shear strains. [less ▲]

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See detailBrain mechanisms underlying prospective thinking of sustainable behaviours
Brevers, Damien UL; Baeken, Chris; Maurage, Pierre et al

in Nature Sustainability (2021)

The preservation of our environment requires sustainable ways of thinking and living. Here, we aimed to explore the core network of brain regions involved in the prospective thinking about (un)sustainable ... [more ▼]

The preservation of our environment requires sustainable ways of thinking and living. Here, we aimed to explore the core network of brain regions involved in the prospective thinking about (un)sustainable behaviours. Using a neuroimaging cue-exposure paradigm, we requested participants (n = 86) to report behaviours that were the most feasible for them to implement (sustainable behaviour) or diminish (unsustainable behaviour) in the future. We find that increasing sustainable behaviours was perceived to be more feasible than reducing unsustainable ones. Consistent with the role of the ventromedial prefrontal cortex and hippocampus in providing access to new representations of past behaviours, we observed stronger activation of these regions when picturing an increase in sustainable behaviours. Critically, simulating the reduction of unsustainable behaviours triggered activation within the right dorsolateral prefrontal cortex (a key region for inhibitory-control processes), which was negatively associated with hippocampal activation (a key region for memory). These findings suggest that the dorsolateral prefrontal cortex downregulates brain regions that support memory retrieval of unsustainable behaviours. This mechanism could inhibit the access to episodic details associated with unsustainable behaviours and in turn allow for prospective thinking of sustainable behaviours. These findings provide an initial step towards a better understanding of the brain networks that are involved in the adoption of sustainable habits. [less ▲]

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See detailLa controverse constitutionnelle grecque sur l’article 120 § 4 en période de crise. Réflexions sur la compétence controversée du peuple en tant qu’organe de l’État
Mavrouli, Roila UL

Doctoral thesis (2021)

Cette thèse s’intéresse à l’apparition des deux discours doctrinaux grecs durant la période de crise économique de 2008 visant l’(in)constitutionnalité du premier mémorandum d’austérité, suivant les ... [more ▼]

Cette thèse s’intéresse à l’apparition des deux discours doctrinaux grecs durant la période de crise économique de 2008 visant l’(in)constitutionnalité du premier mémorandum d’austérité, suivant les politiques européennes de négociation de la dette publique. Il s’agit de faire apparaître les limites entre le discours du droit, la dogmatique juridique et la science du droit tout en identifiant trois niveaux de langage. La doctrine en tant qu’activité de compréhension, d’explication, de création et de critique du droit se distingue de la connaissance du droit positif. Mais parfois par crainte qu’une vision sociologique du droit ne prive celui-ci de toute prévisibilité, la doctrine se replie sur elle-même en fondant sa « science » et par conséquent prétend à une connaissance de son objet-droit. Ainsi, il s’agit de rechercher si le discours doctrinal pro-mémorandum autant que le discours doctrinal anti-mémorandum ne seraient pas descriptifs, mais exprimeraient des valeurs et énonceraient des prescriptions. Ou bien si la doctrine ne se limitant pas à une activité de connaissance de son objet, elle interprèterait et systématiserait le droit dans son rôle créateur de source complémentaire du droit en dialogue constant avec la jurisprudence et le législateur. Ou bien encore si elle peut être caractérisée par un élément scientifique, à savoir la description critique de l’activité scientifique ou prétendument scientifique à propos du droit. À cet égard, la démarche épistémologique de cette analyse est de montrer que la science juridique, aujourd’hui confrontée à une crise du paradigme positiviste dominant, mène à penser soit la nécessité de changer les dogmes établis soit au fait que l’« anomalie » ne sera pas parvenue à infirmer la fécondité du paradigme en place. [less ▲]

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See detailReview: Mapping Modern Jewish Cultures
Zaagsma, Gerben UL

in Reviews in the Digital Humanities (2021), 2(1),

Review of the website Mapping Modern Jewish Cultures (https://richbrew.org/).

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See detailFeasible Point Pursuit and Successive Convex Approximation for Transmit Power Minimization in SWIPT-Multigroup Multicasting Systems
Gautam, Sumit UL; Lagunas, Eva UL; Chatzinotas, Symeon UL et al

in IEEE Transactions on Green Communications and Networking (2021)

We consider three wireless multi-group (MG) multicasting (MC) systems capable of handling heterogeneous user types viz., information decoding (ID) specific users with conventional receiver architectures ... [more ▼]

We consider three wireless multi-group (MG) multicasting (MC) systems capable of handling heterogeneous user types viz., information decoding (ID) specific users with conventional receiver architectures, energy harvesting (EH) only users with non-linear EH module, and users with joint ID and EH capabilities having separate units for the two operations, respectively. Each user is categorized under unique group(s), which can be of MC type specifically meant for ID users, and/or an energy group consisting of EH explicit users. The joint ID and EH users are a part of both EH group and single MC group. We formulate an optimization problem to minimize the total transmit power with optimal precoder designs for the three aforementioned scenarios, under certain quality-of-service constraints. The problem may be adapted to the well-known semidefinite program and solved via relaxation of rank-1 constraint. However, this process leads to performance degradation in some cases, which increases with the rank of solution obtained from the relaxed problem. Hence, we develop a novel technique motivated by the feasible-point pursuit successive convex approximation method in order to address the rank-related issue. The benefits of proposed method are illustrated under various operating conditions and parameter values, with comparison between the three above-mentioned scenarios. [less ▲]

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See detailOn the Weyl problem for complete surfaces in the hyperbolic and anti-de Sitter spaces
Schlenker, Jean-Marc UL

E-print/Working paper (2021)

The classical Weyl problem (solved by Lewy, Alexandrov, Pogorelov, and others) asks whether any metric of curvature K≥0 on the sphere is induced on the boundary of a unique convex body in $\R^3$. The ... [more ▼]

The classical Weyl problem (solved by Lewy, Alexandrov, Pogorelov, and others) asks whether any metric of curvature K≥0 on the sphere is induced on the boundary of a unique convex body in $\R^3$. The answer was extended to surfaces in hyperbolic space by Alexandrov in the 1950s, and a ``dual'' statement, describing convex bodies in terms of the third fundamental form of their boundary (e.g. their dihedral angles, for an ideal polyhedron) was later proved. We describe three conjectural generalizations of the Weyl problem in $\HH^3$ and its dual to unbounded convex subsets and convex surfaces, in ways that are relevant to contemporary geometry since a number of recent results and well-known open problems can be considered as special cases. One focus is on convex domain having a ``thin'' asymptotic boundary, for instance a quasicircle -- this part of the problem is strongly related to the theory of Kleinian groups. A second direction is towards convex subsets with a ``thick'' ideal boundary, for instance a disjoint union of disks -- here one find connections to problems in complex analysis, such as the Koebe circle domain conjecture. A third direction is towards complete, convex disks of infinite area in $\HH^3$ and surfaces in hyperbolic ends -- with connections to questions on circle packings or grafting on the hyperbolic disk. Similar statements are proposed in anti-de Sitter geometry, a Lorentzian cousin of hyperbolic geometry where interesting new phenomena can occur, and in Minkowski and Half-pipe geometry. We also collect some partial new results mostly based on recent works. [less ▲]

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See detailIntergenerational wealth transfers and wealth inequality in rich countries: What do we learn from Gini decomposition?
Nolan, Brian; Palomino, Juan C.; van Kerm, Philippe UL et al

in Economics Letters (2021), 199

The role of intergenerational transfers of wealth via inheritance and gifts inter vivos in the accumulation of household wealth and the generation of wealth inequality has been hotly debated. This paper ... [more ▼]

The role of intergenerational transfers of wealth via inheritance and gifts inter vivos in the accumulation of household wealth and the generation of wealth inequality has been hotly debated. This paper uses data from household wealth surveys for six rich countries – Britain, France, Germany, Italy, Spain and the US – to assess the contribution of intergenerational wealth transfers to wealth inequality using decomposition methods for the Gini coefficient. The results show that transfer wealth is consistently a good deal more unequally distributed than non-transfer wealth and total wealth. Transfer wealth accounts for only about one-tenth of overall wealth inequality for the US compared to one-third for Germany and Italy. This mirrors the importance of transfer wealth in total wealth in each country, with differences in inequality in transfer wealth and its correlation with total wealth having only a modest impact. We find that a marginal percentage increase in all transfers reduces total wealth inequality in Britain, Germany and the US, while it would increase total wealth inequality in France, Italy and Spain. [less ▲]

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See detailWhy serve soup with a fork?: How policy coherence for development can link environmental impact assessment with the 2030 agenda for sustainable development
Koff, Harlan UL

in Environmental Impact Assessment Review (2021), 86

The Sustainable Development Goals (SDGs) re-focused development cooperation on universal and transformative development aimed at improving the quality of life of people in all world regions, while ... [more ▼]

The Sustainable Development Goals (SDGs) re-focused development cooperation on universal and transformative development aimed at improving the quality of life of people in all world regions, while simultaneously conserving natural resources. Critics, however, have correctly questioned whether appropriate policy methods and tools exist for the adequate implementation of transformative development. These challenges are even more significant given that the implementation of the SDGs falls to nation-states. This article asks “Can the transformative development promoted by the SDG’s be achieved through the policy tools presently utilized by nation-states, such as environmental impact assessment (EIA)?” The study responds to this question through a critical examination of EIA in Mexico in relation to mining. Empirical analysis focuses on the proposed Caballo Blanco open-pit mine in Veracruz state. The case can be considered critical because it is often presented as a success, given that a broad coalition of actors prevented the mine from opening through activities directed at EIA. This article questions this narrative because it shows how EIA actually can undermine transformative development through the use of cost-benefit logics. The article concludes that policy coherence for development (PCD) can potentially support EIA as a methodology through which transformative development can be promoted. PCD can improve the “normative effectiveness” of EIA when used as an evaluation criteria. Otherwise, EIA may undermine the implementation of the SDGs which would be comparable to serving soup with a fork. [less ▲]

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See detailVertex Feature Encoding and Hierarchical Temporal Modeling in a Spatio-Temporal Graph Convolutional Network for Action Recognition
Papadopoulos, Konstantinos UL; Ghorbel, Enjie UL; Aouada, Djamila UL et al

in International Conference on Pattern Recognition, Milan 10-15 January 2021 (2021, January)

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See detailTaxation of the Platform Economy: Challenges and Lessons for Social Security
Pantazatou, Aikaterini UL

in Becker, Ulrich; Chesalina, Olga (Eds.) Social Law 4.0: New Approaches for Ensuring Financing Social Security in the Digital Age (2021)

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See detailModelling of residually stressed, extended and inflated cylinders with application to aneurysms
Font, Alejandro; Jha, Niraj Kumar; Dehghani, Hamidreza UL et al

in Mechanics Research Communications (2021), 111

The paper presents the localized bifurcation abnormal enlargement associated with certain human diseases such as abdominal aortic aneurysms (AAA), among others. The constitutive framework herewith ... [more ▼]

The paper presents the localized bifurcation abnormal enlargement associated with certain human diseases such as abdominal aortic aneurysms (AAA), among others. The constitutive framework herewith proposed is constructed relying on the modelling of non-linear elastic materials under the action of residual stresses. The suitable incorporation on the mechanical response of residual stresses in the analysis is regarded important for the formation of aneurysms in soft tissues. From a mechanical perspective, the onset of aneurysms formation can be interpreted through bifurcation conditions, whose localization is relatively sensitive to different material and geometrical parameters as it is shown here. In order to reduce the risk and interpret aneurysm formation, we perform a thorough sensitivity analysis of the effect of design parameters such as tube diameter, length, thickness and strength of the residual stress field on bifurcation of a tube under inflation and extesion. A consistent residually stressed material model is formulated in terms of invariants for a general elastic strain-energy function. The dependence of applied pressure, axial stretch and different geometrical and constitutive parameters on bulging and bending bifurcation is illustrated. The numerical procedure to analyse the bifurcation of the finite deformation boundary-value problem at hand is developed based on the modified Riks method. The proposed formulation is implemented in the general-purpose finite element code ABAQUS using user-defined material subroutines.For a given material model, bulging bifurcation is expected for sufficiently large values of the axial stretch while the onset of bifurcation is found to be the bending mode for small values of the axial stretch. This transition zone from bending bifurcation to bulging bifurcation is analyzed for the different parameters considered. [less ▲]

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See detailComputational Stem Cell Biology: Open Questions and Guiding Principles
Del Sol Mesa, Antonio UL

in Cell Stem Cell (2021)

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See detailCovid19 et la re-présentation du corps
Becker, Katrin UL

in Kuriyama; de Leonardis, Ota; Sonnenschein, Carlos (Eds.) et al Covid-19 - Tour du Monde (2021)

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See detailResource Allocation for AF Relaying Wireless-Powered Networks with Nonlinear Energy Harvester
Nguyen, Tien-Tung; Nguyen, van Dinh UL; Pham, Quoc-Viet et al

in IEEE Communications Letters (2021), 25(1), 1089-7798

This letter considers a relay-based wireless-powered communication network to assist wireless communication between a source and multiple users. In particular, the relay adopts a nonlinear energy model to ... [more ▼]

This letter considers a relay-based wireless-powered communication network to assist wireless communication between a source and multiple users. In particular, the relay adopts a nonlinear energy model to harvest energy from a power beacon and subsequently uses it for information transmission over timedivision multiple access. Aiming at the maximization of end-toend (e2e) sum throughput, we formulate a novel optimization problem that jointly optimizes the power and time fraction for energy and information transmission. For a simple yet efficient solution for the nonconvex problem, we first convert it to a more computationally tractable problem and then develop an iterative algorithm, in which closed-form solutions are obtained at each iteration. The effectiveness of our proposed approach is verified and demonstrated through simulation results. Moreover, the results reveal that the source should transmit with its maximum allowable power budget to obtain the optimal e2e sum throughput. [less ▲]

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