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See detailThe edge-based strain smoothing method for compressible and nearly incompressible non-linear elasticity for solid mechanics
Lee, Chang-Kye; Mihai, L. Angela; Kerfriden, Pierre et al

E-print/Working paper (in press)

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See detailYolanda von Vianden und das Yolanda-Epos
Sieburg, Heinz UL

E-print/Working paper (in press)

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See detailFunctional inequalities on path space of sub-Riemannian manifolds and applications
Cheng, Li Juan UL; Grong, Erlend; Thalmaier, Anton UL

E-print/Working paper (2019)

For sub-Riemannian manifolds with a chosen complement, we first establish the derivative formula and integration by parts formula on path space with respect to a well-defined gradient operator. By using ... [more ▼]

For sub-Riemannian manifolds with a chosen complement, we first establish the derivative formula and integration by parts formula on path space with respect to a well-defined gradient operator. By using these formulae, we then show that upper and lower bounds of the horizontal Ricci curvature correspond to functional inequalities on path space analogous to what has been established in Riemannian geometry by Aaron Naber, such as gradient inequalities, log-Sobolev and Poincaré inequalities. [less ▲]

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See detailDer Arbeitsmarkt der Sozialen Arbeit 2018 = Le marché de l'emploi du secteur social en 2018
Flammang, Manou Laure UL; Böwen, Petra UL

E-print/Working paper (2019)

This newsletter describes the job market in the social work sector in Luxembourg in 2018. The data are derived from an ongoing research project by the "PraxisBüro" of the University of Luxembourg. The ... [more ▼]

This newsletter describes the job market in the social work sector in Luxembourg in 2018. The data are derived from an ongoing research project by the "PraxisBüro" of the University of Luxembourg. The newsletter presents a selection of statistics concerning for example the most sought after qualification levels, the distribution of practice fields, the distribution of job offers in public, municipal, private and non-governmental organisations and the documented gap between the demand of social workers with a Bachelor diploma and the number of Bachelor diplomas issued in Luxembourg. [less ▲]

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See detailExpediting in Two-Echelon Spare Parts Inventory Systems
Drent, Melvin UL; Arts, Joachim UL

E-print/Working paper (2019)

We consider a two-echelon spare parts inventory system consisting of one central warehouse and multiple local warehouses. Each warehouse keeps multiple types of repairable parts to maintain several types ... [more ▼]

We consider a two-echelon spare parts inventory system consisting of one central warehouse and multiple local warehouses. Each warehouse keeps multiple types of repairable parts to maintain several types of capital goods. The local warehouses face Poisson demand and are replenished by the central warehouse. We assume that unsatisfied demand is backordered at all warehouses. Furthermore, we assume deterministic lead times for the replenishments of the local warehouses. The repair shop at the central warehouse has two repair options for each repairable part: a regular repair option and an expedited repair option. Both repair options have stochastic lead times. Irrespective of the repair option, each repairable part uses a certain resource for its repair. Assuming a dual-index policy at the central warehouse and base stock control at the local warehouses, an exact and efficient evaluation procedure for a given control policy is formulated. To find an optimal control policy, we look at the minimization of total investment costs under constraints on both the aggregate mean number of backorders per capital good type and the aggregate mean fraction of repairs that are expedited per repair resource. For this non-linear non-convex integer programming problem, we develop a greedy heuristic and an algorithm based on decomposition and column generation. Both solution approaches perform very well with average optimality gaps of 1.56 and 0.23 percent, respectively, across a large test bed of industrial size. Based on a case study at Netherlands Railways, we show how managers can significantly reduce the investment in repairable spare parts when dynamic repair policies are leveraged to prioritize repair of parts whose inventory is critically low. [less ▲]

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See detailThe dual volume of quasi-Fuchsian manifolds and the Weil-Petersson distance
Mazzoli, Filippo UL

E-print/Working paper (2019)

Making use of the dual Bonahon-Schläfli formula, we prove that the dual volume of the convex core of a quasi-Fuchsian manifold M is bounded by an explicit constant, depending only on the topology of M ... [more ▼]

Making use of the dual Bonahon-Schläfli formula, we prove that the dual volume of the convex core of a quasi-Fuchsian manifold M is bounded by an explicit constant, depending only on the topology of M, times the Weil-Petersson distance between the hyperbolic structures on the upper and lower boundary components of the convex core of M. [less ▲]

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See detailFuturistic Project Becoming a Reality: Self-Driving Cars in Luxembourg
Vukovich, Lilla UL; Vysotskaya, Volha UL

E-print/Working paper (2019)

Detailed reference viewed: 73 (16 UL)
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See detailWHY IS THE MARKET SKEWNESS-RETURN RELATIONSHIP NEGATIVE?
Lehnert, Thorsten UL

E-print/Working paper (2019)

Detailed reference viewed: 80 (3 UL)
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See detailPrice Pressure and the Market Skewness Risk Premium
Lehnert, Thorsten UL

E-print/Working paper (2019)

Detailed reference viewed: 43 (0 UL)
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See detailInexact Block Coordinate Descent Algorithms for Nonsmooth Nonconvex Optimization
Yang, Yang UL; Pesavento, Marius; Luo, Zhi-Quan et al

E-print/Working paper (2019)

In this paper, we propose an inexact block coordinate descent algorithm for large-scale nonsmooth nonconvex optimization problems. At each iteration, a particular block variable is selected and updated by ... [more ▼]

In this paper, we propose an inexact block coordinate descent algorithm for large-scale nonsmooth nonconvex optimization problems. At each iteration, a particular block variable is selected and updated by solving the original optimization problem with respect to that block variable inexactly. More precisely, a local approximation of the original optimization problem is solved. The proposed algorithm has several attractive features, namely, i) high flexibility, as the approximation function only needs to be strictly convex and it does not have to be a global upper bound of the original function; ii) fast convergence, as the approximation function can be designed to exploit the problem structure at hand and the stepsize is calculated by the line search; iii) low complexity, as the approximation subproblems are much easier to solve and the line search scheme is carried out over a properly constructed differentiable function; iv) guaranteed convergence to a stationary point, even when the objective function does not have a Lipschitz continuous gradient. Interestingly, when the approximation subproblem is solved by a descent algorithm, convergence to a stationary point is still guaranteed even if the approximation subproblem is solved inexactly by terminating the descent algorithm after a finite number of iterations. These features make the proposed algorithm suitable for large-scale problems where the dimension exceeds the memory and/or the processing capability of the existing hardware. These features are also illustrated by several applications in signal processing and machine learning, for instance, network anomaly detection and phase retrieval. [less ▲]

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See detailTo be or not to be: How the Luxembourgish government is preparing for Brexit
Vysotskaya, Volha UL; Vukovich, Lilla UL; Bissinger, Jutta UL et al

E-print/Working paper (2019)

This article summarizes the potential impact of BREXIT on Luxembourg (as seen by April 2019).

Detailed reference viewed: 80 (24 UL)
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See detailCorporate Governance and Skewness in Stock Returns
Berglund, Tom; Lehnert, Thorsten UL; Rolle, Gudrun

E-print/Working paper (2019)

This paper analyzes the relationship between corporate governance and idiosyncratic skewness of stock returns. We test this hypothesis by analyzing the impact of external as well as internal governance ... [more ▼]

This paper analyzes the relationship between corporate governance and idiosyncratic skewness of stock returns. We test this hypothesis by analyzing the impact of external as well as internal governance provisions, and are thus able to provide an overall understanding of the relationship between governance and firm-specific return asymmetries. Our results show that better governance leads to a reduction in idiosyncratic skewness in relatively non-competitive industries. In relatively competitive industries, governance has less to no impact on firm-specific return skewness. Furthermore, an overall increase in transparency, quality and disclosure of information, proxied through the Sarbanes Oxley Act, reduces relative idiosyncratic skewness. Our findings can be regarded as detrimental for shareholders, who have a preference for positive idiosyncratic skewness. The evidence contributes to a debate, which suggests that – at the end of the day – an act like Sarbanes-Oxley, which was intended to protect shareholders from accounting errors and frauds and to improve the accuracy of corporate disclosures, comes at the expenses of shareholders. The reduction of idiosyncratic skewness through better governance collides with shareholder’s preference for idiosyncratic and positively skewed stock returns, which present a lottery like upside option of monetary gains and value creation through the right tail. This side effect of governance is also in line with the literature that highlights potential costs of corporate governance. [less ▲]

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See detailFear and Euphoria
Lehnert, Thorsten UL

E-print/Working paper (2019)

Detailed reference viewed: 48 (1 UL)
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See detailA System and Method for Monitoring Controlling and Troubleshooting of Abrasive Waterjet Cutting Apparatus
Copertaro, Edoardo UL

E-print/Working paper (2019)

The invention consists of a system and method for monitoring, controlling and troubleshooting of Abrasive Waterjet Cutting machinery. More in detail, the method exploits a network of sensors for ... [more ▼]

The invention consists of a system and method for monitoring, controlling and troubleshooting of Abrasive Waterjet Cutting machinery. More in detail, the method exploits a network of sensors for continuously monitor its vibroacoustic emission pattern. Relevant features are extracted from the data using an iterative processing method. Deviations from a benchmark are interpreted based on model training then used for automatic control and troubleshooting. The expected outcome is an improvement of waterjet automation and robustness to the excellence of Industry 4.0 with a consequent impact on both its cost effectiveness and the provided quality assurance. [less ▲]

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

E-print/Working paper (2019)

Detailed reference viewed: 66 (8 UL)
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See detailDifferential graded Lie groups and their differential graded Lie algebras
Jubin, Benoît; Kotov, Alexei; Poncin, Norbert UL et al

E-print/Working paper (2019)

Detailed reference viewed: 39 (2 UL)
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See detailUC Updatable Non-Hiding Committed Database with Efficient Zero-Knowledge Proofs
Rial Duran, Alfredo UL

E-print/Working paper (2019)

We define an ideal functionality $\Functionality_{\DB}$ and a protocol $\mathrm{\Pi_{\DB}}$ for an updatable non-hiding committed database ($\DB$). $\DB$ is described as the task of storing a database ... [more ▼]

We define an ideal functionality $\Functionality_{\DB}$ and a protocol $\mathrm{\Pi_{\DB}}$ for an updatable non-hiding committed database ($\DB$). $\DB$ is described as the task of storing a database into a suitable data structure that allows you to efficiently prove in zero-knowledge (ZK) that a value is stored in the database at a certain position. The database is \emph{non-hiding} because both prover and verifier know its content. It is \emph{committed} in the sense that only ZK proofs about position-value pairs that are actually stored are possible. It is \emph{updatable} because its contents can be modified dynamically throughout the protocol execution. The $\DB$ task is used implicitly as building block of privacy-preserving protocols for e-commerce, smart billing and access control. In those protocols, this task is intertwined with others. Our functionality $\Functionality_{\DB}$ allows us to study constructions for this task in isolation. Furthermore, it allows us to improve modularity in protocol design, by using $\Functionality_{\DB}$ as building block of those protocols along with functionalities for other tasks. Our construction $\mathrm{\Pi_{\DB}}$ uses a non-hiding vector commitment (VC) scheme as building block. Thanks to the efficiency properties of non-hiding VC schemes, $\mathrm{\Pi_{\DB}}$ provides ZK proofs whose computation cost (after initialization) and whose size are both independent of the database size. Therefore, $\mathrm{\Pi_{\DB}}$ is suitable for large databases. Moreover, the database can be updated dynamically and very efficiently. [less ▲]

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See detailAn introduction to the theory of unconditionally secure message authentication using the constructive cryptography framework
Ostrev, Dimiter UL

E-print/Working paper (2019)

We provide an introduction to certain ideas from the theory of unconditionally secure message authentication. We explain the notions of impersonation and substitution attacks, and explain how protection ... [more ▼]

We provide an introduction to certain ideas from the theory of unconditionally secure message authentication. We explain the notions of impersonation and substitution attacks, and explain how protection against these two types of attack implies composable, information theoretic security. We explain the relation of authentication protocols to universal hashing. We give both probabilistic and explicit constructions proving the existence of one way authentication protocols using a short secret key and we prove matching lower bounds on the required secret key size. Then, we turn attention to interactive authentication protocols. We explain the message size reduction technique used by Gemmell and Naor and later Naor, Segev and Smith, and how it leads to protocols with secret key size independent of the message length. We also prove a matching lower bound on the secret key entropy. We generalize the lower bound proof of Naor, Segev and Smith and remove the assumption that the message is revealed in the first flow of the protocol. [less ▲]

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See detailBianchi's additional symmetries
Rahm, Alexander UL

E-print/Working paper (2019)

Detailed reference viewed: 25 (1 UL)
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See detailTrigonometry for the multiples of 3 degrees
Perucca, Antonella UL; Stranen, Deborah UL

E-print/Working paper (2019)

Detailed reference viewed: 35 (4 UL)
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Peer Reviewed
See detailSocial division in the market: conspicous consumption with nationalist feelings
Zanaj, Skerdilajda UL

E-print/Working paper (2019)

In this paper, we explore the effects of conspicuous goods as a means of social division between native citizens and migrants. We push forward the hypothesis that choosing a particular good can confer a ... [more ▼]

In this paper, we explore the effects of conspicuous goods as a means of social division between native citizens and migrants. We push forward the hypothesis that choosing a particular good can confer a sense of place. We introduce this idea in an international vertical differentiation market with two variants and two social groups: migrants and natives. Natives are narrow-minded since they attribute a positive social value to the variant that complies with their own consumption culture. Migrants are open-minded. When consumers belonging to different groups meet, they exchange information about their consumption habits and consumption well-being that reveals their consumption culture: narrow-minded versus open-minded. Consequently, after meeting, some consumers may change beliefs (narrow-minded to open-minded or vice versa) and consumption choices. Using a dynamic model, we fully elucidate the steady-state equilibrium and highlight the impact of nationalism on migrant integration. [less ▲]

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See detailUC Priced Oblivious Transfer with Purchase Statistics and Dynamic Pricing
Damodaran, Aditya Shyam Shankar UL; Dubovitskaya, Maria; Rial Duran, Alfredo UL

E-print/Working paper (2019)

Priced oblivious transfer (POT) is a cryptographic protocol that can be used to protect customer privacy in e-commerce applications. Namely, it allows a buyer to purchase an item from a seller without ... [more ▼]

Priced oblivious transfer (POT) is a cryptographic protocol that can be used to protect customer privacy in e-commerce applications. Namely, it allows a buyer to purchase an item from a seller without disclosing to the latter which item was purchased and at which price. Unfortunately, existing POT schemes have some drawbacks in terms of design and functionality. First, the design of existing POT schemes is not modular. Typically, a POT scheme extends a k-out-of-N oblivious transfer (OT) scheme by adding prices to the items. However, all POT schemes do not use OT as a blackbox building block with certain security guarantees. Consequently, security of the OT scheme needs to be reanalyzed while proving security of the POT scheme, and it is not possible to swap the underlying OT scheme with any other OT scheme. Second, existing POT schemes do not allow the seller to obtain any kind of statistics about the buyer's purchases, which hinders customer and sales management. Moreover, the seller is not able to change the prices of items without restarting the protocol from scratch. We propose a POT scheme that addresses the aforementioned drawbacks. We prove the security of our POT in the UC framework. We modify a standard POT functionality to allow the seller to receive aggregate statistics about the buyer's purchases and to change prices dynamically. We present a modular construction for POT that realizes our functionality in the hybrid model. One of the building blocks is an ideal functionality for OT. Therefore, our protocol separates the tasks carried out by the underlying OT scheme from the additional tasks needed by a POT scheme. Thanks to that, our protocol is a good example of modular design and can be instantiated with any secure OT scheme as well as other building blocks without reanalyzing security from scratch. [less ▲]

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See detailKummer theory for number fields and the reductions of algebraic numbers
Perucca, Antonella UL; Sgobba, Pietro UL

E-print/Working paper (2019)

For all number fields the failure of maximality for the Kummer extensions is bounded in a very strong sense. We give a direct proof (without relying on the Bashmakov-Ribet method) of the fact that if G is ... [more ▼]

For all number fields the failure of maximality for the Kummer extensions is bounded in a very strong sense. We give a direct proof (without relying on the Bashmakov-Ribet method) of the fact that if G is a finitely generated and torsion-free multiplicative subgroup of a number field K having rank r, then the ratio between n^r and the Kummer degree [K(\zeta_n,\sqrt[n]{G}):K(\zeta_n)] is bounded independently of n. We then apply this result to generalise to higher rank a theorem of Ziegler from 2006 about the multiplicative order of the reductions of algebraic integers (the multiplicative order must be in a given arithmetic progression, and an additional Frobenius condition may be considered). [less ▲]

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See detailThe War of Rare Earth Elements: A Dynamic Games Approach
Bertinelli, Luisito UL; Poncin, Stéphane Louis Maxim UL; Zou, Benteng UL

E-print/Working paper (2019)

Rare earth elements govern today’s high-tech world and are deemed to be essential for the attainment of sustainable development goals. Since the 1990s, these elements have been predominantly supplied by ... [more ▼]

Rare earth elements govern today’s high-tech world and are deemed to be essential for the attainment of sustainable development goals. Since the 1990s, these elements have been predominantly supplied by one single actor, China. However, due to the increasing global relevance of their availability, other countries are now encouraged to enter the market. The objective of this paper is to analyze the strategic interactions among (potential) suppliers. In particular, we are interested in (1) the optimal timing for a newcomer (e.g. the U.S.) to enter the market, (2) the incumbent’s (i.e. China’s) optimal behavior, and (3) the cost-efficiency of cooperative vs. competitive market relations. By setting up a continuous-time dynamic game model, we show that (1) the newcomer should postpone the production launch until its rare earth reserves coincide with those of the incumbent, (2) the incumbent should strive for a late market entry and therefore keep its monopolistic resource extraction at the lowest possible level, (3) compared to the payoffs under competition, cooperation leads to a Pareto improvement when started at an early stage. The findings of our model are particularly relevant for the rational strategic positioning of the two great powers, America and China. [less ▲]

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See detailROBUST BAYES-LIKE ESTIMATION: RHO-BAYES ESTIMATION
Baraud, Yannick UL; Birgé, Lucien

E-print/Working paper (2019)

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See detailAddendum to: Reductions of algebraic integers
Perucca, Antonella UL; Sgobba, Pietro UL; Tronto, Sebastiano UL

E-print/Working paper (2019)

Let K be a number field, and let G be a finitely generated and torsion-free subgroup of K*. We consider Kummer extensions of G of the form K(\zeta_{2^m}, \sqrt[2^n]G)/K(\zeta_{2^m}), where n \leq m. In ... [more ▼]

Let K be a number field, and let G be a finitely generated and torsion-free subgroup of K*. We consider Kummer extensions of G of the form K(\zeta_{2^m}, \sqrt[2^n]G)/K(\zeta_{2^m}), where n \leq m. In the paper "Reductions of algebraic integers" (J. Number Theory, 2016) by Debry and Perucca, the degrees of those extensions have been evaluated in terms of divisibility parameters over K(\zeta_4). We prove how properties of G over K explicitly determine the divisibility parameters over K(\zeta_4). This result has a clear computational advantage, since no field extension is required. [less ▲]

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See detailConcise UC Zero-Knowledge Proofs for Oblivious Updatable Databases
Camenisch, Jan; Dubovitskaya, Maria; Rial Duran, Alfredo UL

E-print/Working paper (2019)

We propose an ideal functionality $\Functionality_{\COMD}$ and a construction for oblivious and updatable committed databases. $\Functionality_{\COMD}$ allows a prover to read, write, and update values in ... [more ▼]

We propose an ideal functionality $\Functionality_{\COMD}$ and a construction for oblivious and updatable committed databases. $\Functionality_{\COMD}$ allows a prover to read, write, and update values in a database and to prove to a verifier in zero-knowledge that a value is read from or written into a certain position. The following properties must hold: (1) values stored in the database remain hidden from the verifier; (2) a value read from a certain position is equal to the value previously written into that position; (3) (obliviousness) both the value read or written and its position remain hidden from the verifier. We describe a construction for $\Functionality_{\COMD}$ based on vector commitments. After the initialization phase, the cost of zero-knowedge proofs for reading and writing is independent of the database size, outperforming other techniques that achieve cost sublinear in the dataset size for prover and/or verifier. Therefore, our construction is especially appealing for cases with large datasets. Finally, we show how to use $\Functionality_{\COMD}$ as a building block in ``commit-and-prove'' two-party protocols, i.e.\ protocols where the prover commits to her inputs and subsequently proves in zero-knowledge statements about the committed values. In comparison to simply using commitment schemes, our construction allows the prover to hide positions read or written efficiently, which is useful to design protocols for e.g.\ cloud-based services, blockchain, privacy-preserving location sharing services and e-commerce, and efficient OR proofs. [less ▲]

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Peer Reviewed
See detailCluster Analysis for Investment funds portfolio optimisation: A symbolic data approach
Terraza, Virginie UL; Toque, Carole

E-print/Working paper (2019)

Detailed reference viewed: 50 (1 UL)
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See detailA hyper-reduction method using adaptivity to cut the assembly costs of reduced order models
Hale, Jack UL; Schenone, Elisa; Baroli, Davide UL et al

E-print/Working paper (2019)

At every iteration or timestep of the online phase of some reduced-order modelling schemes, large linear systems must be assembled and then projected onto a reduced order basis of small dimension. The ... [more ▼]

At every iteration or timestep of the online phase of some reduced-order modelling schemes, large linear systems must be assembled and then projected onto a reduced order basis of small dimension. The projected small linear systems are cheap to solve, but assembly and projection are now the dominant computational cost. In this paper we introduce a new hyper-reduction strategy called reduced assembly (RA) that drastically cuts these costs. RA consists of a triangulation adaptation algorithm that uses a local error indicator to con- struct a reduced assembly triangulation specially suited to the reduced order basis. Crucially, this reduced assembly triangulation has fewer cells than the original one, resulting in lower assembly and projection costs. We demonstrate the efficacy of RA on a Galerkin-POD type reduced order model (RAPOD). We show performance increases of up to five times over the baseline Galerkin-POD method on a non-linear reaction-diffusion problem solved with a semi-implicit time-stepping scheme and up to seven times for a 3D hyperelasticity problem solved with a continuation Newton-Raphson algorithm. The examples are implemented in the DOLFIN finite element solver using PETSc and SLEPc for linear algebra. Full code and data files to produce the results in this paper are provided as supplementary material. [less ▲]

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See detailExponential integrability and exit times of diffusions on sub-Riemannian and RCD*(K,N) spaces
Thompson, James UL; Thalmaier, Anton UL

E-print/Working paper (2019)

In this article we derive moment estimates, exponential integrability, concentration inequalities and exit times estimates for canonical diffusions in two settings each beyond the scope of Riemannian ... [more ▼]

In this article we derive moment estimates, exponential integrability, concentration inequalities and exit times estimates for canonical diffusions in two settings each beyond the scope of Riemannian geometry. Firstly, we consider sub-Riemannian limits of Riemannian foliations. Secondly, we consider the non-smooth setting of RCD*(K,N) spaces. In each case the necessary ingredients are an Ito formula and a comparison theorem for the Laplacian, for which we refer to the recent literature. As an application, we derive pointwise Carmona-type estimates on eigenfunctions of Schrodinger operators. [less ▲]

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See detailConsumption home bias and ethnocentrism: an international duopoly
Zanaj, Skerdilajda UL

E-print/Working paper (2019)

We define a model with two countries and two vertically differentiated goods, a high and a low-quality variant, and heterogenous consumers with respect to their willingness to pay for quality. Consumers ... [more ▼]

We define a model with two countries and two vertically differentiated goods, a high and a low-quality variant, and heterogenous consumers with respect to their willingness to pay for quality. Consumers in one country are ethnocentric in consumption. They thrive additional satisfaction when consuming a domestic good rather than a foreign one since only the former can satisfy their sense of place. We investigate the role of trade costs and ethnocentric attitude in shaping the equilibrium configuration of the international duopoly. [less ▲]

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See detailClassifications of quasitrivial semigroups
Devillet, Jimmy UL; Marichal, Jean-Luc UL; Teheux, Bruno UL

E-print/Working paper (2018)

We investigate classifications of quasitrivial semigroups defined by certain equivalence relations. The subclass of quasitrivial semigroups that preserve a given total ordering is also investigated. In ... [more ▼]

We investigate classifications of quasitrivial semigroups defined by certain equivalence relations. The subclass of quasitrivial semigroups that preserve a given total ordering is also investigated. In the special case of finite semigroups, we address and solve several related enumeration problems. [less ▲]

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See detailMobbing in der Schule / Harcèlement à l’école
Heinz, Andreas UL; van Duin, Claire UL; Kern, Matthias Robert UL et al

E-print/Working paper (2018)

In der Kindheit und Jugend gemobbt zu werden ist ein Risikofaktor für schlechtere Schulleistungen, aber langfristig auch für Angststörungen im Erwachsenenalter. Daher wurde in der HBSC-Studie 2014 gefragt ... [more ▼]

In der Kindheit und Jugend gemobbt zu werden ist ein Risikofaktor für schlechtere Schulleistungen, aber langfristig auch für Angststörungen im Erwachsenenalter. Daher wurde in der HBSC-Studie 2014 gefragt, wie häufig die Schüler in den vergangenen Monaten in der Schule gemobbt wurden. 73 % waren nicht von Mobbing betroffen, 16 % wurden 1- bis 2-mal gemobbt und 11 % wurden mindestens 2-mal pro Monat gemobbt. Ältere Schüler waren seltener Opfer von Mobbing als jüngere Schüler, wobei Jungen und Mädchen in allen Altersgruppen ähnlich häufig betroffen waren. Dementsprechend waren die Schüler des Fondamental und des Modulaire häufiger betroffen als die Schüler des Secondaire technique und des Secondaire. Schüler, die aus Familien mit einem geringen Wohlstandsniveau stammen, waren häufiger Mobbingopfer als Schüler aus wohlhabenden Familien. Mit der Häufigkeit des Mobbings sinkt die Lebenszufriedenheit und die Zahl der Gesundheitsbeschwerden steigt. [less ▲]

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See detailTägliches Essen von Obst und Gemüse / Consommation quotidienne de fruits et de légumes
van Duin, Claire UL; Residori, Caroline UL; Kern, Matthias Robert UL et al

E-print/Working paper (2018)

Ein hoher Gemüse- und Obstverzehr ist Teil eines gesunden Lebensstils. In der HBSC-Studie 2014 wurden die Schüler daher gefragt, wie häufig sie Obst und Gemüse essen: 37 % gaben an, täglich Obst zu essen ... [more ▼]

Ein hoher Gemüse- und Obstverzehr ist Teil eines gesunden Lebensstils. In der HBSC-Studie 2014 wurden die Schüler daher gefragt, wie häufig sie Obst und Gemüse essen: 37 % gaben an, täglich Obst zu essen und 32 % gaben den täglichen Verzehr von Gemüse an. Schüler der Altersgruppe 11-12 essen häufiger Obst und Gemüse als Schüler im Alter von 13-18. Der tägliche Konsum von Obst und Gemüse ist bei Mädchen häufiger als bei Jungen. Des Weiteren ist der tägliche Konsum bei Schülern aus wohlhabenden Familien weiter verbreitet als bei Schülern aus nicht wohlhabenden Familien. Schüler des Fondamental und des Enseignement secondaire geben einen täglichen Verzehr häufiger an als Schüler des Enseignement secondaire technique und des Modulaire. [less ▲]

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See detailBewertung des Klassenklimas / Climat de classe
van Duin, Claire UL; Heinz, Andreas UL; Kern, Matthias Robert UL et al

E-print/Working paper (2018)

In der HBSC-Studie 2014 sollten die Schüler die folgende Aussage zum Klassenklima bewerten: „Die meisten Schüler in meiner Klasse sind nett und hilfsbereit.“ 72 % stimmen dieser Aussage zu, 10 % lehnen ... [more ▼]

In der HBSC-Studie 2014 sollten die Schüler die folgende Aussage zum Klassenklima bewerten: „Die meisten Schüler in meiner Klasse sind nett und hilfsbereit.“ 72 % stimmen dieser Aussage zu, 10 % lehnen sie ab und 18 % wählen die neutrale Mittelkategorie. Getrennt nach Alter und Geschlecht zeigen sich kaum Unterschiede im wahrgenommenen Klassenklima. Allerdings bewerten Schüler des Fondamental und des Secondaire das Klassenklima besser als Schüler des Secondaire technique und des Modulaire. Je besser das Klassenklima bewertet wird, desto zufriedener sind die Schüler mit ihrem Leben und desto mehr mögen sie die Schule. [less ▲]

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See detailKörperliche Aktivität von Schülern in ihrer Freizeit / Activité physique des élèves pendant leur temps libre
Heinz, Andreas UL; Kern, Matthias Robert UL; Residori, Caroline UL et al

E-print/Working paper (2018)

In der HBSC-Studie 2014 wurden die Schüler gefragt, wie häufig sie in ihrer Freizeit so aktiv sind, dass sie außer Atem oder ins Schwitzen kommen. Rund jeder zehnte Schüler ist nach eigenen Angaben nie ... [more ▼]

In der HBSC-Studie 2014 wurden die Schüler gefragt, wie häufig sie in ihrer Freizeit so aktiv sind, dass sie außer Atem oder ins Schwitzen kommen. Rund jeder zehnte Schüler ist nach eigenen Angaben nie körperlich aktiv, rund jeder sechste ist hingegen an 7 Stunden oder häufiger pro Woche aktiv. Im internationalen Vergleich sind die luxemburgischen Schüler überdurchschnittlich häufig körperlich aktiv. Allerdings nimmt die Aktivität im Laufe der Jugend ab und bestimmte Gruppen sind aktiver als andere: Jungen sind in allen Altersgruppen aktiver als Mädchen und Kinder aus wohlhabenden Familien sind aktiver als Kinder aus nicht wohlhabenden Familien. Schüler des Enseignement secondaire sind aktiver als Schüler des Modulaire. [less ▲]

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See detailFernsehkonsum von Schülern / Consommation de télévision
van Duin, Claire UL; Heinz, Andreas UL; Kern, Matthias Robert UL et al

E-print/Working paper (2018)

In der HBSC-Studie 2014 wurden die Schüler gefragt, wie lange sie an einem Wochentag fernsehen. Knapp 8 % geben an, nicht fernzusehen, weitere 19 % schauen eine halbe Stunde fern. 57 % schauen 2 Stunden ... [more ▼]

In der HBSC-Studie 2014 wurden die Schüler gefragt, wie lange sie an einem Wochentag fernsehen. Knapp 8 % geben an, nicht fernzusehen, weitere 19 % schauen eine halbe Stunde fern. 57 % schauen 2 Stunden oder mehr fern, was als häufiger TV-Konsum definiert wird. Bei Schülern im Alter von 13-18 ist häufiger TV-Konsum weiter verbreitet als bei Schülern im Alter von 11-12. Des Weiteren ist häufiger TV-Konsum verbreiteter bei Schülern des Secondaire technique als bei Schülern des Fondamental sowie des Secondaire. Schüler, die davon ausgehen, dass ihre Lehrer sie für leistungsschwach halten, schauen häufiger Fernsehen als Schüler, die denken, dass ihre Lehrer sie für überdurchschnittlich leistungsfähig halten. [less ▲]

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See detailQualität der Kommunikation in der Familie / Qualité de la communication au sein de la famille
Heinz, Andreas UL; Kern, Matthias Robert UL; Residori, Caroline UL et al

E-print/Working paper (2018)

In der HBSC-Studie 2014 sollten die Schüler vier Aussagen zur Qualität der Kommunikation in ihrer Familie auf einer Skala von 1 (= niedrige Qualität) bis 5 (= hohe Qualität) bewerten. Über 80 % vergeben ... [more ▼]

In der HBSC-Studie 2014 sollten die Schüler vier Aussagen zur Qualität der Kommunikation in ihrer Familie auf einer Skala von 1 (= niedrige Qualität) bis 5 (= hohe Qualität) bewerten. Über 80 % vergeben gute Bewertungen im Bereich von 4 oder 5. Rund 12 % der Schüler bewerten die Qualität der Familienkommunikation im mittleren Bereich (3) und 5 % vergeben niedrige Bewertungen (1 oder 2). Ältere Schüler bewerten die Familienkommunikation schlechter als jüngere. Dementsprechend bewerten Schüler des Fondamental die Familienkommunikation besser als Schüler von Sekundarschulen. Schüler, die eine hohe Qualität angeben, berichten eine geringere Zahl von Gesundheitsbeschwerden. [less ▲]

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Peer Reviewed
See detailElectryo, In-person Voting with Transparent Voter Verifiability and Eligibility Verifiability
Roenne, Peter UL; Ryan, Peter UL; Zollinger, Marie-Laure UL

E-print/Working paper (2018)

Selene is an e-voting protocol that allows voters to directly check their individual vote, in cleartext, in the final tally via a tracker system, while providing good coercion mitigation. This is in ... [more ▼]

Selene is an e-voting protocol that allows voters to directly check their individual vote, in cleartext, in the final tally via a tracker system, while providing good coercion mitigation. This is in contrast to conventional, end-to-end verifiable schemes in which the voter verifies the presence of an encryption of her vote on the bulletin board. The Selene mechanism can be applied to many e-voting schemes, but here we present an application to the polling station context, resulting in a voter-verifiable electronic tally with a paper audit trail. The system uses a smartcard-based public key system to provide the individual verifica- tion and universal eligibility verifiability. The paper record contains an encrypted link to the voter’s identity, requiring stronger assumptions on ballot privacy than normal paper voting, but with the benefit of pro- viding good auditability and dispute resolution as well as supporting (comparison) risk limiting audits. [less ▲]

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See detailInvariance in a class of operations related to weighted quasi-geometric means
Devillet, Jimmy UL; Matkowski, Janusz

E-print/Working paper (2018)

Let $I\subset (0,\infty )$ be an interval that is closed with respect to the multiplication. The operations $C_{f,g}\colon I^{2}\rightarrow I$ of the form \begin{equation*} C_{f,g}\left( x,y\right) =\left ... [more ▼]

Let $I\subset (0,\infty )$ be an interval that is closed with respect to the multiplication. The operations $C_{f,g}\colon I^{2}\rightarrow I$ of the form \begin{equation*} C_{f,g}\left( x,y\right) =\left( f\circ g\right) ^{-1}\left( f\left( x\right) \cdot g\left( y\right) \right) \text{,} \end{equation*} where $f,g$ are bijections of $I$ are considered. Their connections with generalized weighted quasi-geometric means is presented. It is shown that invariance\ question within the class of this operations leads to means of iterative type and to a problem on a composite functional equation. An application of the invariance identity to determine effectively the limit of the sequence of iterates of some generalized quasi-geometric mean-type mapping, and the form of all continuous functions which are invariant with respect to this mapping are given. The equality of two considered operations is also discussed. [less ▲]

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Peer Reviewed
See detailThe re-constitutionalisation of the EMU after the economic crisis
Zaccaroni, Giovanni UL

E-print/Working paper (2018)

Detailed reference viewed: 27 (1 UL)
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See detailModel Uncertainty and Pricing Performance in Option Valuation
Bams, Dennis; Blanchard, Gildas; Lehnert, Thorsten UL

E-print/Working paper (2018)

The objective of this paper is to evaluate option pricing model performance at the cross sectional level. For this purpose, we propose a statistical framework, in which we in particular account for the ... [more ▼]

The objective of this paper is to evaluate option pricing model performance at the cross sectional level. For this purpose, we propose a statistical framework, in which we in particular account for the uncertainty associated with the reported pricing performance. Instead of a single figure, we determine an entire probability distribution function for the loss function that is used to measure option pricing model performance. This methodology enables us to visualize the effect of parameter uncertainty on the reported pricing performance. Using a data driven approach, we confirm previous evidence that standard volatility models with clustering and leverage effects are sufficient for the option pricing purpose. In addition, we demonstrate that there is short-term persistence but long-term heterogeneity in cross-sectional option pricing information. This finding has two important implications. First, it justifies the practitioner’s routine to refrain from time series approaches, and instead estimate option pricing models on a cross-section by cross-section basis. Second, the long term heterogeneity in option prices pinpoints the importance of measuring, comparing and testing option pricing model for each cross-section separately. To our knowledge no statistical testing framework has been applied to a single cross-section of option prices before. We propose a methodology that addresses this need. The proposed framework can be applied to a broad set of models and data. In the empirical part of the paper, we show by means of example, an application that uses a discrete time volatility model on S&P 500 European options. [less ▲]

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See detailData Filtering Rules in Option Valuation
Bams, Dennis; Blanchard, Gildas; Lehnert, Thorsten UL

E-print/Working paper (2018)

The choice of data filtering rules are, next to model selection and parameter calibration, an important step in an option pricing exercise. We illustrate the implications of data filtering rules, by ... [more ▼]

The choice of data filtering rules are, next to model selection and parameter calibration, an important step in an option pricing exercise. We illustrate the implications of data filtering rules, by investigating three alternative renowned filtering rules in the context of pricing European S&P 500 index options. Different filtering rules result in strongly diverging samples, which carry different information and therefore lead to different parameter estimates. This is illustrated for the Ad Hoc Black-Scholes model. No filtering rule is, in terms of pricing performance, superior on the whole range of options. Instead, each filtering rule is specialized toward better pricing of options types that were included in the calibration sample at the costs of excluded options. Included options are unable to perfectly represent the properties and characteristics of excluded options. In particular, option prices are heterogeneous in the maturity dimension, which is a major driving force underlying the impact of exclusion filters on pricing performance. Additionally, small deviations from the put-call parity strongly affect parameter estimates as well as the accompanying pricing performance. These results emphasize the prominent role of filtering rules as an important implicit choice for an option pricing model calibration. [less ▲]

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See detailThe Subsidy to Infrastructure as an Asset Class*
Kräussl, Roman UL; Andonov, Aleksandar; Rauh, Joshua

E-print/Working paper (2018)

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See detailMarket Skewness Risk, Risk Aversion and the Cross-Section of Stock Returns
Bams, Dennis; Honarvar, Iman; Lehnert, Thorsten UL

E-print/Working paper (2018)

Previous research suggests that the cross section of stock returns has substantial exposure to risks captured by higher moments of market returns, implied by S&P500 index option prices. However, assuming ... [more ▼]

Previous research suggests that the cross section of stock returns has substantial exposure to risks captured by higher moments of market returns, implied by S&P500 index option prices. However, assuming that risk aversion is time-varying, a risk-based explanation would suggest that the exposure is priced in periods of high risk aversion, while it is not necessarily priced/weaker in periods of low risk aversion. We find that for market skewness and kurtosis, this hypothesis is not supported by the data. We find that each of the higher moment prices of risk is time-varying and has significantly different patterns under different market conditions, proxied by a measure of investors’ relative risk aversion. In particular, in line with our reasoning, our results suggest that only in down-markets (high risk aversion periods), the exposure to the market volatility innovations is priced significantly negative in the cross-section of stocks, while it is not priced in up-markets (low risk aversion periods). In contrast, we find that in down-markets, market skewness and kurtosis are not priced risk factors, while the price of market skewness risk is significantly negative and the price of kurtosis risk is positive in up-markets. However, the previously reported results for skewness and kurtosis are counterintuitive, strictly violate the risk compensation principles and, therefore, do not support a risk-based explanation. The results persist even after controlling for the Fama-French and Carhart factors. [less ▲]

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See detailIslamic Banking and Economic Growth: New Evidence
Kchouri, Bilal UL; Lehnert, Thorsten UL

E-print/Working paper (2018)

While extensive work has shown that conventional banking development is generally conducive to economic growth, there are only a limited number of studies that investigate the impact of Islamic banking ... [more ▼]

While extensive work has shown that conventional banking development is generally conducive to economic growth, there are only a limited number of studies that investigate the impact of Islamic banking. Importantly, the literature on conventional banking claims that a reverse causality from economy performance to banking may exists, but existing studies on Islamic banking fail to address this potential endogeneity problem. This paper tackles this problem and explores the relationship between Islamic banking development and economic performance in a sample of 32 developed and developing countries based on data spanning the 2000 to 2016 period. The findings show that, although Islamic banks are considered small relative to the total size of the financial sector, Islamic banking is positively correlated with economic growth even after controlling for financial structure, macroeconomic factors and other variables. The outcome is robust across different econometric specifications like pooling OLS, fixed effects, panel data with over-identified GMM, and dynamic difference GMM. The results are confirmed on two different indicators of Islamic banking and hold for different time periods. [less ▲]

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See detailAsset Pricing Implications of Good Governance
Lehnert, Thorsten UL

E-print/Working paper (2018)

Some of the world’s poorest countries have demonstrated that political leadership and practical policies make a difference. Good governance could help to strengthen accountability, enhance participation ... [more ▼]

Some of the world’s poorest countries have demonstrated that political leadership and practical policies make a difference. Good governance could help to strengthen accountability, enhance participation and break down inequalities. Furthermore, a country’s quality of government has a positive effect on the development of its financial market and equity returns. In particular, it lowers equity volatility and, therefore, the costs of equity financing, which further helps to reduce inequalities. While price jumps are prevalent in stock markets all over the world, previous literature provides little guidance about the international nature of jumps and its relationship with country characteristics. Jumps are found to be far less systematic than the smooth (non-jump) component of country price indexes. Hence, if jumps are more idiosyncratic, governance should primarily affect the jump risk component of stock market volatility. This is good news for international investors, because diversification provides insurance against jumps. Relying on an equilibrium asset-pricing model in an economy under jump diffusion, I decompose the moments of the returns of international stock markets into a diffusive (systematic) risk and a (idiosyncratic) jump risk part. Using stock market data for a balanced panel of 52 countries, my results suggest that risk governance is an important determinant of (idiosyncratic) jump risk. Stock markets in poorly governed countries are characterized by higher volatility and more negative return asymmetry, primarily driven by the higher jump risk. Among the different governance indicators analyzed, the regulatory quality, the government effectiveness and the control of corruption appear to be most important. Results are robust to the inclusion of various controls for other country- or market-specific characteristics. My results have important policy implications. [less ▲]

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See detail"Was hältst du zurzeit von der Schule?" / « Actuellement que penses-tu de l’école? »
van Duin, Claire UL; Heinz, Andreas UL; Kern, Matthias Robert UL et al

E-print/Working paper (2018)

Die Schule ist ein wichtiger Ort der Sozialisation, an dem die Schüler viel Zeit verbringen. Positive Erfahrungen mit der Schule können die soziale und gesundheitliche Entwicklung der Schüler fördern ... [more ▼]

Die Schule ist ein wichtiger Ort der Sozialisation, an dem die Schüler viel Zeit verbringen. Positive Erfahrungen mit der Schule können die soziale und gesundheitliche Entwicklung der Schüler fördern, negative Erfahrungen können die Entwicklung beeinträchtigen. Daher wurde in der HBSC-Studie 2014 gefragt, wie sehr die Schüler ihre Schule mögen. Von den 11-12-Jährigen mögen 30 % die Schule sehr, weitere 52 % mögen sie einigermaßen. In der Gruppe der 15-16-Jährigen mögen 11 % die Schule sehr und 15 % mögen sie überhaupt nicht. Dementsprechend mögen Schüler des Fondamental ihre Schule eher als Schüler an Sekundarschulen. Zwischen den Schultypen Secondaire, Secondaire technique und Modulaire gibt es hingegen kaum Unterschiede. Je mehr sich Schüler durch die Schularbeit gestresst fühlen, desto eher mögen sie die Schule nicht. Sie mögen sie auch dann eher nicht, wenn sie vermuten, dass ihre Lehrer sie für leistungsschwach halten. Je weniger die Schüler ihre Schule mögen, desto mehr Gesundheitsbeschwerden berichten sie. [less ▲]

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See detailFrühstückgewohnheiten / Habitudes du petit déjeuner
Residori, Caroline UL; van Duin, Claire UL; Kern, Matthias Robert UL et al

E-print/Working paper (2018)

In der HBSC-Studie 2014 wurden die Schüler gefragt, ob sie an allen Schultagen frühstücken. Tägliches Frühstücken nimmt mit dem Alter ab: Während im Alter von 11-12 rund zwei Drittel der Schüler täglich ... [more ▼]

In der HBSC-Studie 2014 wurden die Schüler gefragt, ob sie an allen Schultagen frühstücken. Tägliches Frühstücken nimmt mit dem Alter ab: Während im Alter von 11-12 rund zwei Drittel der Schüler täglich frühstücken, sind es weniger als die Hälfte der Schüler im Alter von 17-18. Im Alter von 11-16 ist tägliches Frühstücken bei Jungen häufiger verbreitet als bei Mädchen, in der Altersgruppe 17-18 gibt es keine Unterschiede. Die befragten Schüler frühstücken umso eher täglich, je höher der Wohlstand der Familie ist, in der sie aufwachsen. Tägliches Frühstücken ist bei Schülern im Fondamental häufiger verbreitet als bei Schülern an Sekundarschulen. Innerhalb der Sekundarschulen ist tägliches Frühstücken am weitesten verbreitet im Enseignement secondaire und am seltensten im Modulaire. [less ▲]

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See detailSchulischer Stress / Le stress à l‘école
van Duin, Claire UL; Heinz, Andreas UL; Kern, Matthias Robert UL et al

E-print/Working paper (2018)

In der HBSC-Studie wurde den Schülern die Frage gestellt: „Fühlst du dich durch die Schularbeit gestresst?“ Insgesamt antworteten 21 % „überhaupt nicht“, 44 % „ein bisschen“, 19 % „einigermaßen“ und 17 ... [more ▼]

In der HBSC-Studie wurde den Schülern die Frage gestellt: „Fühlst du dich durch die Schularbeit gestresst?“ Insgesamt antworteten 21 % „überhaupt nicht“, 44 % „ein bisschen“, 19 % „einigermaßen“ und 17 % „sehr“. Je älter die Schüler sind, desto häufiger geben sie an, unter Schulstress zu leiden. Unter den älteren Schülern sind Mädchen eher von Schulstress betroffen als Jungen. Am häufigsten fühlen sich Schüler des Enseignement secondaire von der Schularbeit gestresst, am seltensten Schüler des Fondamentals, Schüler des Secondaire technique liegen dazwischen. Schüler, die davon ausgehen, dass ihre Lehrer sie für überdurchschnittlich leistungsfähig halten, geben seltener Schulstress an als Schüler, die annehmen, dass ihre Lehrer sie für durchschnittlich oder unterdurchschnittlich leistungsfähig halten. Schüler, die einen stärkeren Schulstress angeben, geben auch an, unter mehr Gesundheitsbeschwerden zu leiden (Kopf-, Bauch- und Rückenschmerzen, Traurigkeit, Gereiztheit, Nervosität, Einschlafschwierigkeiten und Schwindel). [less ▲]

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See detail« Actuellement que penses-tu de l’école? »
van Duin, Claire UL; Heinz, Andreas UL; Kern, Matthias Robert UL et al

E-print/Working paper (2018)

L'école est un lieu important de socialisation dans lequel les élèves passent beaucoup de temps. Les expériences positives en lien avec l’école peuvent favoriser leur développement social et celui de leur ... [more ▼]

L'école est un lieu important de socialisation dans lequel les élèves passent beaucoup de temps. Les expériences positives en lien avec l’école peuvent favoriser leur développement social et celui de leur santé, tandis que les expériences négatives peuvent perturber leur développement. Par conséquent, l'étude HBSC de 2014 a demandé à quel point les élèves aimaient leur école. Parmi les 11-12 ans, 30 % disent aimer beaucoup l'école et 52 % l'aiment un peu. Dans le groupe des 15-16 ans, 11 % disent aimer beaucoup l'école et 15 % ne l'aiment pas du tout. En conséquence, les élèves du fondamental sont plus nombreux à aimer beaucoup l’école que les élèves du secondaire. Cependant, il n'y a pratiquement pas de différences entre les écoles secondaires classique, technique et modulaire. En outre, plus les élèves se sentent stressés par les devoirs, moins ils aiment l'école. Ils ont également tendance à ne pas l’aimer quand ils soupçonnent que leurs enseignants les considèrent comme n’étant pas assez performants. Enfin, moins les élèves aiment leur école, plus ils signalent de problèmes de santé. [less ▲]

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See detailAlkoholkonsum von Schülern in Luxemburg / La consommation d’alcool des élèves au Luxembourg
Catunda, Carolina UL; van Duin, Claire UL; Kern, Matthias Robert UL et al

E-print/Working paper (2018)

In der HBSC-Studie 2014 wurden die Schüler gefragt, ob sie in den vergangenen 30 Tagen Alkohol getrunken haben. Von den 11-12-Jährigen gaben dies 4 % an, in der Altersgruppe 17-18 waren es 68 %. Bis zum ... [more ▼]

In der HBSC-Studie 2014 wurden die Schüler gefragt, ob sie in den vergangenen 30 Tagen Alkohol getrunken haben. Von den 11-12-Jährigen gaben dies 4 % an, in der Altersgruppe 17-18 waren es 68 %. Bis zum Alter von 16 Jahren geben Jungen und Mädchen ähnlich häufig Alkoholkonsum an. In der Altersgruppe 17-18 haben männliche Jugendliche häufiger als weibliche Jugendliche Alkohol getrunken (73 % vs. 63 % in den vergangenen 30 Tagen). Ältere Jugendliche aus wohlhabenden Familien gaben häufiger Alkoholkonsum an als Jugendliche aus Familien mit geringem Wohlstand (74 % vs. 63 %). Zudem konsumieren die 15-18-jährigen Schüler des Enseignement secondaire häufiger Alkohol als die Schüler des Enseignement secondaire technique. Verglichen mit 15-jährigen Schülern aus anderen Ländern geben die luxemburgischen Schüler seltener an, bereits zweimal oder häufiger in ihrem Leben betrunken gewesen zu sein. [less ▲]

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See detailGeschlechtsverkehr und Verhütung / Activité sexuelle et contraception
van Duin, Claire UL; Heinz, Andreas UL; Kern, Matthias Robert UL et al

E-print/Working paper (2018)

In der HBSC-Studie 2014 wurden den Schülern von Sekundarschulen Fragen zu Sexualität und Verhütung gestellt. Von den männlichen Jugendlichen im Alter von 15 Jahren gaben 27 % an, schon Geschlechtsverkehr ... [more ▼]

In der HBSC-Studie 2014 wurden den Schülern von Sekundarschulen Fragen zu Sexualität und Verhütung gestellt. Von den männlichen Jugendlichen im Alter von 15 Jahren gaben 27 % an, schon Geschlechtsverkehr gehabt zu haben, bei den weiblichen Jugendlichen liegt der Anteil mit 22 % etwas darunter. Von den 18-Jährigen gaben jeweils rund zwei Drittel an, schon mit jemandem geschlafen zu haben. Schüler des Enseignement secondaire technique geben häufiger als ihre Altersgenossen im Enseignement secondaire an, schon Geschlechtsverkehr gehabt zu haben. Bei ihrem letzten Geschlechtsverkehr haben 68 % mit Kondomen verhütet und 55 % mit der Pille. Jungen wussten häufiger als die Mädchen nicht, welche Verhütungsmittel sie genutzt haben. Dies deutet darauf hin, dass Jungen in Verhütungsfragen sorgloser sind und ein Teil von ihnen Verhütung als Frauensache ansieht. Rund 3 % der sexuell aktiven Schüler gaben ein riskantes Verhütungsverhalten an: Sie haben beim letzten Geschlechtsverkehr mittels Koitus interruptus verhütet und sie haben auf andere Methoden verzichtet oder sie wussten nicht, ob der Partner bzw. die Partnerin zusätzlich eine sichere Methode einsetzt. [less ▲]

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See detailCannabiskonsum von Schülern in Luxemburg / Consommation de cannabis des élèves au Luxembourg
Heinz, Andreas UL; Kern, Matthias Robert UL; Residori, Caroline UL et al

E-print/Working paper (2018)

In der HBSC-Studie 2014 wurde nach dem Cannabiskonsum der Schüler gefragt. 38 % der 17-18-Jährigen haben laut eigenen Angaben mindestens einmal in ihrem Leben Cannabis probiert, in den vergangenen 30 ... [more ▼]

In der HBSC-Studie 2014 wurde nach dem Cannabiskonsum der Schüler gefragt. 38 % der 17-18-Jährigen haben laut eigenen Angaben mindestens einmal in ihrem Leben Cannabis probiert, in den vergangenen 30 Tagen haben in dieser Altersgruppe 15 % Cannabis konsumiert. Der „Probierkonsum“ ist somit deutlich weiter verbreitet als der regelmäßige Konsum. Je älter die Schüler sind, desto höher ist der Anteil der Cannabiskonsumenten, wobei der Anstieg bei den Jungen größer ist als bei den Mädchen. Von den 17-18-Jährigen haben 20 % der Jungen in den vergangenen 30 Tagen Cannabis genommen, aber nur 11 % der Mädchen. Die Häufigkeit des Konsums unterscheidet sich kaum je nach Wohlstand der Familie oder zwischen dem Enseignement secondaire und dem Enseignement secondaire technique. Ein Viertel der Konsumenten hat bis zum Alter von rund 14 Jahren mit dem Konsum angefangen, daher sollte die Prävention frühzeitig einsetzen. [less ▲]

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See detailTabakkonsum von Schülern in Luxemburg / Consommation de tabac par les élèves au Luxembourg
Kern, Matthias Robert UL; Heinz, Andreas UL; Residori, Caroline UL et al

E-print/Working paper (2018)

In der HBSC-Studie 2014 wurden Fragen zum Tabakkonsum gestellt. Von den 11-12-Jährigen sind 2 % laut eigenen Angaben Raucher, in der Altersgruppe 17-18 steigt dieser Anteil auf knapp über ein Drittel. Bis ... [more ▼]

In der HBSC-Studie 2014 wurden Fragen zum Tabakkonsum gestellt. Von den 11-12-Jährigen sind 2 % laut eigenen Angaben Raucher, in der Altersgruppe 17-18 steigt dieser Anteil auf knapp über ein Drittel. Bis zum Alter von 14 Jahren ist der Anteil der regelmäßigen Raucher (d.h. sie rauchen mindestens einmal pro Woche) bei Jungen und Mädchen etwa gleich hoch. In der Altersgruppe 17-18 rauchen 32 % der männlichen Jugendlichen regelmäßig, aber nur 23 % der weiblichen Jugendlichen. Im Enseignement secondaire technique ist der Anteil der regelmäßigen Raucher in allen Altersgruppen ungefähr doppelt so hoch wie im Enseignement secondaire. Die Hälfte der Raucher hat mit 14 Jahren oder noch früher mit dem Rauchen angefangen, daher sollte frühzeitig über die Gefahren des Rauchens aufgeklärt werden. [less ▲]

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See detailSignaling or Marketing? The Role of Discount Control Mechanisms
Kräussl, Roman UL; Polletc, Joshua; Stefanova, Denitsa UL

E-print/Working paper (2018)

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See detailThe Performance of Marketplace Lenders:
Kräussl, Roman UL; Kräussl, Zsofia UL; Pollet, Joshua et al

E-print/Working paper (2018)

Detailed reference viewed: 108 (29 UL)
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See detailLes problèmes de santé des élèves luxembourgeois
Heinz, Andreas UL; Kern, Matthias Robert UL; Catunda, Carolina UL et al

E-print/Working paper (2018)

Dans le cadre de l’enquête HBSC 2014, réalisée dans plusieurs pays de l’Union européenne, les élèves interrogés devaient indiquer la fréquence à laquelle ils souffraient des huit problèmes de santé ... [more ▼]

Dans le cadre de l’enquête HBSC 2014, réalisée dans plusieurs pays de l’Union européenne, les élèves interrogés devaient indiquer la fréquence à laquelle ils souffraient des huit problèmes de santé suivants : maux de tête ou de dos, douleurs abdominales, tristesse, irritabilité, nervosité, difficultés à s’endormir ou vertiges. Le résultat démontre que 41 % des élèves affirmaient avoir plusieurs fois par semaine voire quotidiennement au moins deux des huit problèmes précités. Les filles souffrent plus fréquemment de problèmes de santé que les garçons, ainsi que les élèves plus âgés comparativement aux plus jeunes. En outre, des enfants issus de familles avec un niveau socio-économique faible ont plus souvent des problèmes de santé que les enfants des familles ayant un niveau socio-économique élevé. Enfin, les élèves du secondaire technique et du modulaire souffrent plus fréquemment de problèmes de santé que les élèves de l’enseignement fondamental et du secondaire. [less ▲]

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See detailLe surpoids chez les élèves au Luxembourg
Kern, Matthias Robert UL; Heinz, Andreas UL; Catunda, Carolina UL et al

E-print/Working paper (2018)

Dans le cadre de l’enquête HBSC 2014, réalisée dans plusieurs pays de l’Union européenne, les élèves étaient interrogés concernant leur taille et leur poids pour permettre de calculer leur indice de masse ... [more ▼]

Dans le cadre de l’enquête HBSC 2014, réalisée dans plusieurs pays de l’Union européenne, les élèves étaient interrogés concernant leur taille et leur poids pour permettre de calculer leur indice de masse corporelle (IMC). Parmi les participants, 13 % sont trop maigres, 72 % ont un poids normal, 13 % sont en surpoids et 3 % sont obèses. En comparant avec les autres pays, il y a relativement peu d’enfants de 11 ans au Luxembourg en surpoids. La proportion des élèves de 15 ans en situation de surpoids se trouve au niveau de la moyenne internationale. Les enfants issus de familles de niveau socio-économique élevé ont un risque plus faible d’être en surpoids que ceux des familles avec un niveau plus bas. Les élèves de l’enseignement fondamental et du secondaire sont moins susceptibles d’être en surpoids que ceux du secondaire technique et du modulaire. [less ▲]

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See detailLa satisfaction de vie des élèves au Luxembourg
Kern, Matthias Robert UL; Heinz, Andreas UL; Catunda, Carolina UL et al

E-print/Working paper (2018)

Dans le cadre de l’enquête HBSC 2014, les élèves devaient indiquer à quel point ils étaient satisfaits de leur vie. La valeur « 0 » signifiait « la plus mauvaise vie possible » et la valeur « 10 » ... [more ▼]

Dans le cadre de l’enquête HBSC 2014, les élèves devaient indiquer à quel point ils étaient satisfaits de leur vie. La valeur « 0 » signifiait « la plus mauvaise vie possible » et la valeur « 10 » signifiait « la meilleur vie possible ». Parmi les participants du Luxembourg, 82 % ont indiqué une valeur de 6 ou plus, ce qui est défini comme étant « un niveau de satisfaction de vie élevé ». Pour 10 % d’entre eux, la satisfaction de vie était cotée avec la valeur moyenne de 5 et les 8 % restants ont indiqué une valeur inférieure à 5. La satisfaction de vie des filles moins âgées est plus élevée que celle des filles plus âgées. Chez les garçons, par contre, la satisfaction de vie reste pratiquement constante de 11 à 18 ans. Les garçons sont plus satisfaits de leur vie que les filles, ainsi que les enfants issus des familles avec un niveau socio-économique élevé, en comparaison avec ceux issus des familles ayant un niveau socio-économique faible. La satisfaction de vie est également liée aux problèmes de santé : les élèves qui indiquent souffrir fréquemment de douleurs, de tristesse, de mauvaise humeur / d’irritabilité, de nervosité, de problèmes à s’endormir ou de vertiges sont moins souvent satisfaits de leur vie. [less ▲]

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See detailRussians in Luxembourg: Русские в Вильтце - история первых эмигрантов
Ganschow, Inna UL

E-print/Working paper (2018)

Люксембургская русская община ведет свой отсчет с 1927 года – десятой годовщины Февральской, а потом и Октябрьской, революции. Девяносто лет назад прибыли эмигранты, прошедшие Гражданскую войну и ... [more ▼]

Люксембургская русская община ведет свой отсчет с 1927 года – десятой годовщины Февральской, а потом и Октябрьской, революции. Девяносто лет назад прибыли эмигранты, прошедшие Гражданскую войну и Крымскую эвакуацию 1920-го, положившую конец сопротивлению Белого движения на Юге России. Приехали в Люксембург, думая, что ненадолго, а остались... навсегда. [less ▲]

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See detailRussians in Luxembourg, WWII: Поиски старого друга
Ganschow, Inna UL

E-print/Working paper (2018)

Спустя семьдесят лет после окончания Второй мировой войны бывший люксембургский военнопленный решил найти своего старого русского друга, которого пригнали на принудительные работы в сталелитейной ... [more ▼]

Спустя семьдесят лет после окончания Второй мировой войны бывший люксембургский военнопленный решил найти своего старого русского друга, которого пригнали на принудительные работы в сталелитейной промышленности и сельском хозяйстве Люксембурга наравне с другими 4.000 узниками. Судьбы двух пленных переплелись, как они переплетутся между советскими и люксембургскими поданными в Европе еще не раз ... [less ▲]

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See detailReliability and Relevance of Fair Values: Private Equity Investments and Investee Fundamentals
Kräussl, Roman UL; Ferreira, Petrus; R. Landsman, Wayne et al

E-print/Working paper (2018)

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See detailWhen Time Breaks: The Hiatus of Refugee Status
Van Der Walt, Johan Willem Gous UL

E-print/Working paper (2018)

“In the first place, we don’t like to be called ‘refugees.’ We ourselves call one another ‘newcomers’ or ‘immigrants.’” Already here, in the first sentence of Arendt’s essay “We Refugees,” does the hiatus ... [more ▼]

“In the first place, we don’t like to be called ‘refugees.’ We ourselves call one another ‘newcomers’ or ‘immigrants.’” Already here, in the first sentence of Arendt’s essay “We Refugees,” does the hiatus of refugee status become manifest. A divide already opens up between different habits of reference. Refugees refer to themselves in one way, non-refugees refer to them in another, and so does the projected or desired possibility of one world in which both refugees and non-refugees might find accommodation, split into two very different realities. Consciousness of the split is of course solely that of the refugees, at first. Initially, the hiatus is theirs only. Others – non-refugees – remain soundly oblivious to this fundamental split until such time as it brutally breaks into their world too, for instance, when the corpse of a four-year old child washes up on a beach, and washes up on every doorstep in a succession of media waves. And then the hiatus is suddenly everywhere and no one remains exempted. As the last sentence of Arendt’s essay contends forcefully, the split begins with the refugee status of some, but it ends with the bigger split of a world that begins to falter and fall apart: “The comity of European peoples went to pieces when, and because, it allowed its weakest member to be excluded and persecuted.” The comity of European peoples show all signs of going to pieces again today. When the comity of peoples goes to pieces, it is not only common space that cracks up, but also common time, the common time that warrants common space according to Kant’s Schematismuslehre. It is ultimately this breaking of time – the hiatus of time – that Arendt thematises elsewhere with reference to “the desolate aimless wanderings of Israeli tribes in the wilderness and the dangers which befell Aeneas before he reached the Italian shore.” “[T]his hiatus,” she continues, obviously creeps into all time speculations which deviate from the currently accepted notion of time as a continuous flow.” (Arendt On Revolution, 205). This text is also a supplementary discussion of my reviews of two recent monographs on Arendt. See: RECENT ARENDT SCHOLARSHIP: Review of The Wandering Thought of Hannah Arendt by Hans Jörg Sigwart, Palgrave MacMillan, 2016, ISBN: 978-1-137-48214-3, 147 pages (abbreviated as WT below), and Rightlessness in an Age of Rights. Hannah Arendt and the Contemporary Struggles of Migrants by Ayten Gündoğdu, New York: Oxford University Press: 2015, 298 pages, forthcoming in Constellations. [less ▲]

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See detailThe Credit Structure Database
Leon, Florian UL

E-print/Working paper (2018)

We describe a new publicly available dataset on credit structure across the world over the period 1995-2014. The database contains two modules. The first part reports the structure of bank loan by types ... [more ▼]

We describe a new publicly available dataset on credit structure across the world over the period 1995-2014. The database contains two modules. The first part reports the structure of bank loan by types of borrowers (households vs. firms). Data are available for 143 countries. Household credit is breakdown between mortgage loans and other household loans (credit cards, car loans, student loans, etc.). Firm credit is decomposed into six sectors (agriculture, industry, construction, transport, trade and other services). The second module contains credit by maturity for 85 countries. Short-term credit is defined as loans with a maturity of one year or less and long-term credit as loans whose maturity exceeds one year. Database is freely available and downlable in Excel and Stata format at the following link: https://sites.google.com/site/florianleon/research/data [less ▲]

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See detailRisk and Refugee Migration
Joxhe, Majlinda UL; Bocqueho, Geraldine; Helstroffer, Jenny et al

E-print/Working paper (2018)

This paper uses the experimental setup of Tanaka et al. (2010) to measure refugees’ risk preferences. A sample of 206 asylum seekers was interviewed in 2017-18 in Luxembourg. Contrary to studies which ... [more ▼]

This paper uses the experimental setup of Tanaka et al. (2010) to measure refugees’ risk preferences. A sample of 206 asylum seekers was interviewed in 2017-18 in Luxembourg. Contrary to studies which focus on risk aversion in general, we analyze its components using a cumulative prospect theory (CPT) framework. We show that refugees exhibit particularly low levels of risk aversion compared to other populations and that CPT provides a better fit for modelling risk attitudes. Moreover, we include randomised temporary treatments provoking emotions and find a small significant impact on probability distortion. Robustness of the Tanaka et al. (2010) experimental framework is confirmed by including treatments regarding the embedding effect. Finally, we propose a theoretical model of refugee migration that integrates the insights from our experimental outcomes regarding the functional form of refugees’ decision under risk and the estimated parameter values. The model is then simulated using the data from our study. [less ▲]

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See detailBlockchain, Fractional Ownership, and the Future of Creative Work
Kräussl, Roman UL; Whitaker, Amy

E-print/Working paper (2018)

While record-making prices at art auctions receive headline news coverage, artists typically do not receive any direct proceeds from those sales. Early-stage creative work in any field is perennially ... [more ▼]

While record-making prices at art auctions receive headline news coverage, artists typically do not receive any direct proceeds from those sales. Early-stage creative work in any field is perennially difficult to value, but the valuation, reward, and incentivization for artistic labor are particularly fraught. A core challenge in studying the real return on artists’ work is the extreme difficulty accessing data from when an artwork was first sold. Galleries keep private records that are difficult to access and to match to public auction results. This paper, for the first time, uses archivally sourced primary market records, for the artists Jasper Johns and Robert Rauschenberg. Although this approach restricts the size of the data set, this innovative method shows much more accurate returns on art than typical regression and hedonic models. We find that if Johns and Rauschenberg had retained 10% equity in their work when it was first sold, the returns to them when the work was resold at auction would have outperformed the US S&P 500 by between 2 and 986 times. The implication of this work opens up vast policy recommendations with regard to secondary art market sales, entrepreneurial strategies using blockchain technology, and implications about how we compensate creative work. [less ▲]

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See detailDo banks and microfinance institutions compete? Microevidence from Madagascar
Leon, Florian UL; Baraton, Pierrick

E-print/Working paper (2018)

In recent years, both microfinance institutions (MFIs) and banks across the world have been converging towards the financing of small enterprises with high financing needs. This paper scrutinizes whether ... [more ▼]

In recent years, both microfinance institutions (MFIs) and banks across the world have been converging towards the financing of small enterprises with high financing needs. This paper scrutinizes whether banks and MFIs compete each other as a result of recent transformations in both industries. In doing so, we study whether the loan strategy of a microfinance institution is shaped by the local presence of a bank. Specifically, we investigate whether bank proximity influences loan conditions provided by one of the largest microfinance institutions in Madagascar. We employ an original panel dataset of 32,374 loans granted to 14,834 borrowers over the period 2008-2014. We find that the closer a bank is located to a given MFI borrower, the larger the loan obtained and the less collateral required. These results are insensitive to several robustness tests for possible endogeneity of distance, sample selection issue, and alternative specifications. In addition, findings are stronger for larger and more established (older) firms in line with our hypothesis. [less ▲]

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See detailLong-term finance and entrepreneurship
Leon, Florian UL

E-print/Working paper (2018)

This paper investigates whether long-term finance affects the firm entry across the world. We construct a new database on short-term and long-term credit provided by commercial banks to the private sector ... [more ▼]

This paper investigates whether long-term finance affects the firm entry across the world. We construct a new database on short-term and long-term credit provided by commercial banks to the private sector in 85 countries over the period 1995-2014. We then analyze whether differences in entrepreneurship are correlated with the provision of short-term and long-term bank credit. Data on entrepreneurship are extracted from two frequently used databases: the Global Entrepreneurship Monitoring dataset and Entrepreneurship Database, each of which captures different aspects of firm creation. Econometric results indicate that long-term credit does not stimulate the firm entry. On the contrary, we find that short-term credit exerts a positive impact at each stage of firm creation from activity birth to registration. Our findings are robust to a battery of sensitivity tests, including additional control variables, alternative dependent variables, alternative sample, and changes in econometric specification. Our findings suggest that better provision of short-term credit allows entrepreneurs to apply for a formal loan instead of relying exclusively on informal loans or internal funds, contrary to long-term loans [less ▲]

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See detailEffect of increasing the ramification on pseudo-deformation rings
Deo, Shaunak UL

E-print/Working paper (2018)

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See detailExecuting Trades in Style: Retail Investors vs. Institutions
Wolff, Christian UL; Ekkayokkaya, Manapol

E-print/Working paper (2018)

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See detailPhase field simulation of early-age fracture in cement-based materials
Nguyen, Thanh Tung UL; Waldmann, Danièle UL; Bui, T. Q.

E-print/Working paper (2018)

Detailed reference viewed: 65 (14 UL)
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See detailBig Moves of Mutual Funds
Lehnert, Thorsten UL

E-print/Working paper (2018)

Detailed reference viewed: 42 (1 UL)
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See detailKrichever-Novikov type algebras. Definitions and Results
Schlichenmaier, Martin UL

E-print/Working paper (2018)

Detailed reference viewed: 19 (0 UL)
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See detailUnderstanding the Babylonian tablet ‘Plimpton 322’ with the decimal system
Perucca, Antonella UL; Stranen, Deborah

E-print/Working paper (2018)

Detailed reference viewed: 42 (1 UL)
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See detailGesundheitsbeschwerden von Schülern in Luxemburg
Heinz, Andreas UL; Kern, Matthias Robert UL; Residori, Caroline UL et al

E-print/Working paper (2017)

Detailed reference viewed: 69 (21 UL)
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See detailDie allgemeine Lebenszufriedenheit von Schülern in Luxemburg
Kern, Matthias Robert UL; Residori, Caroline UL; Heinz, Andreas UL et al

E-print/Working paper (2017)

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See detailÜbergewicht bei Schülern in Luxemburg
Residori, Caroline UL; Kern, Matthias Robert UL; Heinz, Andreas UL et al

E-print/Working paper (2017)

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See detailWho Trade at Better Prices?
Wolff, Christian UL; Ekkayokkaya, Manapol

E-print/Working paper (2017)

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See detailState of the Art in Lightweight Symmetric Cryptography
Biryukov, Alex UL; Perrin, Léo Paul UL

E-print/Working paper (2017)

Lightweight cryptography has been one of the ``hot topics'' in symmetric cryptography in the recent years. A huge number of lightweight algorithms have been published, standardized and/or used in ... [more ▼]

Lightweight cryptography has been one of the ``hot topics'' in symmetric cryptography in the recent years. A huge number of lightweight algorithms have been published, standardized and/or used in commercial products. In this paper, we discuss the different implementation constraints that a ``lightweight'' algorithm is usually designed to satisfy. We also present an extensive survey of all lightweight symmetric primitives we are aware of. It covers designs from the academic community, from government agencies and proprietary algorithms which were reverse-engineered or leaked. Relevant national (\nist{}...) and international (\textsc{iso/iec}...) standards are listed. We then discuss some trends we identified in the design of lightweight algorithms, namely the designers' preference for \arx{}-based and bitsliced-S-Box-based designs and simple key schedules. Finally, we argue that lightweight cryptography is too large a field and that it should be split into two related but distinct areas: \emph{ultra-lightweight} and \emph{IoT} cryptography. The former deals only with the smallest of devices for which a lower security level may be justified by the very harsh design constraints. The latter corresponds to low-power embedded processors for which the \aes{} and modern hash function are costly but which have to provide a high level security due to their greater connectivity. [less ▲]

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See detailWhat makes Data Science different? A discussion involving Statistics2.0 and Computational Sciences
Ley, Christophe; Bordas, Stéphane UL

E-print/Working paper (2017)

Data Science is today one of the main buzzwords be it in business, industrial or academic settings. Machine learning, experimental design, data-driven modelling are all, undoubtedly, rising disciplines if ... [more ▼]

Data Science is today one of the main buzzwords be it in business, industrial or academic settings. Machine learning, experimental design, data-driven modelling are all, undoubtedly, rising disciplines if one goes by the soaring number of research papers and patents appearing each year. The prospect of becoming a ``Data Scientist'' appeals to many. A discussion panel organised as part of the European Data Science Conference (European Association for Data Science (EuADS)) asked the question: ``What makes Data Science different?'' In this paper we give our own, personal and multi-facetted view on this question, from an engineering and a statistics perspective. In particular, we compare Data Science to Statistics and discuss the connection between Data Science and Computational Science. [less ▲]

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See detailMigration, Labor Tasks and Production Structure in Europe
Joxhe, Majlinda UL; Borelli, Stefania; Giuseppe, De Arcangelis

E-print/Working paper (2017)

This paper assesses the effect of the immigration on the production structure in a selection of European countries in 2001-2009 with a task-based approach. The inflow of immigrants represents an increase ... [more ▼]

This paper assesses the effect of the immigration on the production structure in a selection of European countries in 2001-2009 with a task-based approach. The inflow of immigrants represents an increase in the relative supply of manual-physical (or simple) tasks, hence favoring simple-task intensive sectors. We use a new OECD dataset, PIAAC, to calculate the index of simple-task intensity at the country-industry level. The analysis confirms that the increase in migration stocks caused a positive impact on the value added of sectors that use more intensively simple tasks. These effects are more intense when considering countries as Italy and Spain characterized by a recent, rapid and intense inflow of migrants. Endogeneity issues are discussed and instruments based on a gravity approach are used in estimation. [less ▲]

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See detailReal-time Error Control for Surgical Simulation
Bui, Huu Phuoc UL; Tomar, Satyendra UL; Bordas, Stéphane UL

E-print/Working paper (2017)

Real-time simulations are becoming increasingly common for various applications, from geometric design to medical simulation. Two of the main factors concurrently involved in defining the accuracy of ... [more ▼]

Real-time simulations are becoming increasingly common for various applications, from geometric design to medical simulation. Two of the main factors concurrently involved in defining the accuracy of surgical simulations are: the modeling error and the discretization error. Most work in the area has been looking at the above sources of error as a compounded, lumped, overall error. Little or no work has been done to discriminate between modeling error (e.g. needle-tissue interaction, choice of constitutive models) and discretization error (use of approximation methods like FEM). However, it is impossible to validate the complete surgical simulation approach and, more importantly, to understand the sources of error, without evaluating both the discretization error and the modeling error. Our objective is thus to devise a robust and fast approach to measure the discretization error via a posteriori error estimates, which are then used for local remeshing in surgical simulations. To ensure that the approach can be used in clinical practice, the method should be robust enough to deal, as realistically as possible, with the interaction of surgical tools with the organ, and fast enough for real-time simulations. The approach should also lead to an improved convergence so that an economical mesh is obtained at each time step. The final goal is to achieve optimal convergence and the most economical mesh, which will be studied in our future work. [less ▲]

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See detailQuantum moment maps and retracts for bounded symmetric domains
Korvers, Stéphane UL

E-print/Working paper (2017)

Detailed reference viewed: 29 (3 UL)
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See detailWealth accumulation over the life course. The role of disadvantages across the employment history
Ponomarenko, Valentina UL

E-print/Working paper (2017)

In this study wealth is employed as an often neglected but highly stratified well-being measure in sociology. I relate the employment history and especially the accumulating disadvantages like ... [more ▼]

In this study wealth is employed as an often neglected but highly stratified well-being measure in sociology. I relate the employment history and especially the accumulating disadvantages like nonemployment and lower occupations to wealth in old age. In particular, I am interested in determining whether an adverse employment history prevents wealth accumulation and which factors influence wealth accumulation across the life course. I use comparative data from the Survey of Health, Ageing and Retirement and combine it with the retrospective panel SHARELIFE to retrieve information about the complete employment history. The relevance of wealth varies significantly across households and in the wider national context. Hence, a contextual perspective is included to account for the difference in wealth rates and wealth inequality in the European countries. The results show that cumulative nonemployment and employment in lower occupations has significant disadvantages for wealth accumulation in old age. However, large differences for men and women persist. Particularly, the household composition and household factors are decisive in the effectuality of these disadvantages. The relation of life course employment and especially disadvantages to accumulated wealth in old aged is stronger in conservative countries than in other welfare regimes. [less ▲]

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See detailGeneralized Ricci flow II: Existence for complete noncompact manifolds
Li, Yi UL

E-print/Working paper (2017)

Detailed reference viewed: 202 (18 UL)
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See detailHarnack estimates for nonlinear parabolic equations under the Ricci flow
Li, Yi UL; Zhu, Xiaorui

E-print/Working paper (2017)

In this paper, we consider first the Li-Yau Harnack estimates for a nonlinear parabolic equation $\partial_{t}u=\Delta_{t}u-qu -au(\ln u)^{\alpha}$ under the Ricci flow, where $\alpha>0$ is a constant. To ... [more ▼]

In this paper, we consider first the Li-Yau Harnack estimates for a nonlinear parabolic equation $\partial_{t}u=\Delta_{t}u-qu -au(\ln u)^{\alpha}$ under the Ricci flow, where $\alpha>0$ is a constant. To extend these estimates to a more general situation, in the second part, we consider the gradient estimates for a positive solution of the nonlinear parabolic equation $\partial _{t}u=\Delta _{t}u+hu^{p}$ on a Riemannian manifold whose metrics evolve under the geometric flow $\partial _{t}g(t)=-2S_{g(t)}$. To obtain these estimates, we introduce a quantity $\underline{\boldsymbol{S}}$ along the flow which measures whether the tensor $S_{ij}$ satisfies the second contracted Bianchi identity. Under conditions on ${\rm Ric}_{g(t)}, S_{g(t)}$, and $\underline{\boldsymbol{S}}$, we obtain the gradient estimates. [less ▲]

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See detailBounds for the mod 2 cohomology of GL_2(Z[sqrt(-2)][1/2])
Bui, Anh Tuan; Rahm, Alexander UL

E-print/Working paper (2017)

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See detailOn the Naturalness of Mutants
Jimenez, Matthieu UL; Cordy, Maxime UL; Kintis, Marinos UL et al

E-print/Working paper (2017)

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See detailIs gender in the eye of the beholder? Identifying cultural attitudes with art auction prices
Kräussl, Roman UL; Adams, Renée; Navone, Marco et al

E-print/Working paper (2017)

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See detailOnline deliberation: state of the art
Kies, Raphaël UL

E-print/Working paper (2017)

In the last decade, the issue of online deliberation (or web-deliberation) has gained an important visibility among the scholars in the domain of political science, political philosophy, political ... [more ▼]

In the last decade, the issue of online deliberation (or web-deliberation) has gained an important visibility among the scholars in the domain of political science, political philosophy, political communication as well as software designers. It corresponds not only to a topic of analysis – that can be broadly defined as the quantitative and qualitative assessment of the political and public debates online - but also to a democratic model of e-democracy, that aims to shape the different political usage of the web according to the deliberative values. A pertinent way to analyze this broad phenomenon is to subdivide its analysis in three sections which content is partly based on updated findings of my book Promises and Limits of web-deliberation. The first section refers to the deliberative theory on which the empirical research is based. The second section deals with the complex issue of operationalizing the deliberative theory. The last section provides an overview of the online deliberative empirical studies that were conducted this last decade by distinguishing three broad research fields: i) The studies that aim at measuring the usage of the political web-debates and the characteristics of the users; ii) The studies that identify and compare the social and political actors that offer possibilities of online debates; iii) The studies assessing the quality of deliberation in different discursive online settings and the ones aiming at defining the factors that could explain variations in web-deliberation. [less ▲]

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See detailPolynomial quadratic differentials on the complex plane and light-like polygons in the Einstein Universe
Tamburelli, Andrea UL

E-print/Working paper (2017)

We construct geometrically a homeomorphism between the moduli space of polynomial quadratic differentials on the complex plane and light-like polygons in the 2-dimensional Einstein Universe. As an ... [more ▼]

We construct geometrically a homeomorphism between the moduli space of polynomial quadratic differentials on the complex plane and light-like polygons in the 2-dimensional Einstein Universe. As an application, we find a class of minimal Lagrangian maps between ideal polygons in the hyperbolic plane. [less ▲]

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See detailRäumliche Identifikationen und Identifizierungen in Grenzregionen. Das Beispiel der Großregion SaarLorLux
Wille, Christian UL

E-print/Working paper (2017)

In diesem Beitrag wird die Bedeutung von nationalen Grenzen für räumliche Identitäten in Grenzregionen analysiert. Dafür wird ein mehrdimensionales Analysemodell entwickelt und am Beispiel der Großregion ... [more ▼]

In diesem Beitrag wird die Bedeutung von nationalen Grenzen für räumliche Identitäten in Grenzregionen analysiert. Dafür wird ein mehrdimensionales Analysemodell entwickelt und am Beispiel der Großregion SaarLorLux gefragt, wie die Einwohner den Raum repräsentieren und wie sie ihre alltagskulturellen Praktiken räumlich organisieren. Außerdem werden räumliche Projektionen im politischen Diskurs aufgedeckt und rekonstruiert, inwiefern diese eine Grundlage bilden für Identifizierungsprozesse. Der Beitrag zeigt, dass nationale Grenzen in den Identifikations- und Identifizierungsvorgängen der Einwohner der Großregion SaarLorLux trotz grenzüberschreitender Verflechtungen eine wichtige Rolle spielen, aber nicht zwangsläufig als starre Ordnungskategorien. [less ▲]

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