Der Platz des Luxemburgischen im Luxemburger Schulsystem – L’écologie linguistique de la classe au Luxembourg

Scientific Conference (2008)

Der Umbau des Wohlfahrtsstaates in Krisenzeiten: Institutioneller Wandel in Deutschland im intemationalen Vergleich

Book published by Degruyter (2013)

"...der Weg ist natürlich ungemein viel schwieriger...". Leaving Care aus Sicht von Ehemaligen

in Sozialmagazin (2018), 96(7-8), 96

Deregulation shock in product market and unemployment

in Journal of Economic Dynamics & Control (2013), 37(4), 711-734

In a dynamic general equilibrium model with endogenous markups and labor market frictions, we investigate the effects of increased product market competition. Unlike most macroeconomic models of search ... [more ▼]

In a dynamic general equilibrium model with endogenous markups and labor market frictions, we investigate the effects of increased product market competition. Unlike most macroeconomic models of search, we endogenize the labor supply along the extensive margin. We find numerically that a model with endogenous labor force participation decision produces a decline in the unemployment rate which is almost three times larger than that in a model with fixed labor force. For a calibration capturing alternatively the European and the US labor markets, a deregulation episode, which lowers the markup by 3 percentage points, results in a fall in the unemployment rate by 0.17 and 0.05 percentage point, respectively, while the labor share is almost unaffected in the long-run. The sensitivity analysis reveals that product market deregulation is more effective in countries where product and labor market regulations are high, unemployment benefits are small and labor force is more responsive. [less ▲]

Derivation and expansion using only small molecules of human neural progenitors for neurodegenerative disease modeling.

in PLoS ONE (2013), 8(3), 59252

Phenotypic drug discovery requires billions of cells for high-throughput screening (HTS) campaigns. Because up to several million different small molecules will be tested in a single HTS campaign, even ... [more ▼]

Phenotypic drug discovery requires billions of cells for high-throughput screening (HTS) campaigns. Because up to several million different small molecules will be tested in a single HTS campaign, even small variability within the cell populations for screening could easily invalidate an entire campaign. Neurodegenerative assays are particularly challenging because neurons are post-mitotic and cannot be expanded for implementation in HTS. Therefore, HTS for neuroprotective compounds requires a cell type that is robustly expandable and able to differentiate into all of the neuronal subtypes involved in disease pathogenesis. Here, we report the derivation and propagation using only small molecules of human neural progenitor cells (small molecule neural precursor cells; smNPCs). smNPCs are robust, exhibit immortal expansion, and do not require cumbersome manual culture and selection steps. We demonstrate that smNPCs have the potential to clonally and efficiently differentiate into neural tube lineages, including motor neurons (MNs) and midbrain dopaminergic neurons (mDANs) as well as neural crest lineages, including peripheral neurons and mesenchymal cells. These properties are so far only matched by pluripotent stem cells. Finally, to demonstrate the usefulness of smNPCs we show that mDANs differentiated from smNPCs with LRRK2 G2019S are more susceptible to apoptosis in the presence of oxidative stress compared to wild-type. Therefore, smNPCs are a powerful biological tool with properties that are optimal for large-scale disease modeling, phenotypic screening, and studies of early human development. [less ▲]

Derivation of angular velocities of the GRACE satellite formation from the star camera data

Scientific Conference (2013, June)

The presentation discusses possibilites to derive common frame angular velocities from the star cameras in the GRACE system. Generally the star cameras measure the rotation of each satellite independently ... [more ▼]

The presentation discusses possibilites to derive common frame angular velocities from the star cameras in the GRACE system. Generally the star cameras measure the rotation of each satellite independently from the other satellite. However, common frame rotations are also needed for various applications. Specifically in this presentation we discuss the application to a variant of the differential gravimetry approach. In this, angular rates around the crosstrack component of the so-called instantaneous relative reference frame are needed. The latter is a common reference frame formed by the inter-satellite connection of the two GRACE satellites. We will quantify the accuracy demands on the derivation of the angular velocities and discuss the possibilites to meet these demands with existing star camera observations. We will also give an outlook on new possibilites in the determination of the orientation and the derivation of angular velocities offered by the laser ranging instrument which will be used in the GRACE Follow-On mission. [less ▲]

Derivations and differential operators on rings and fields

in Annales Universitatis Scientiarum Budapestinensis de Rolando Eötvös Nominatae. Sectio Computatorica (2018)

Let R be an integral domain of characteristic zero. We prove that a function D : R → R is a derivation of order n if and only if D belongs to the closure of the set of differential operators of degree n ... [more ▼]

Let R be an integral domain of characteristic zero. We prove that a function D : R → R is a derivation of order n if and only if D belongs to the closure of the set of differential operators of degree n in the product topology of R^R, where the image space is endowed with the discrete topology. In other words, f is a derivation of order n if and only if, for every finite set F ⊂ R, there is a differential operator D of degree n such that f = D on F. We also prove that if d1, . . . , dn are nonzero derivations on R, then d1 ◦ . . . ◦ dn is a derivation of exact order n. [less ▲]

Derivations of the Lie algebras of differential operators

in Indagationes Mathematicae (2005), 16(2), 181--200

Derivative and divergence formulae for diffusion semigroups

in Annals of Probability (2019), 47(2), 743-773

Derivative recovery and a posteriori error estimate for extended finite elements

in Computer Methods in Applied Mechanics and Engineering (2007), 196(35-36), 3381-3399

This paper is the first attempt at error estimation for extended finite elements. The goal of this work is to devise a simple and effective local a posteriori error estimate for partition of unity ... [more ▼]

This paper is the first attempt at error estimation for extended finite elements. The goal of this work is to devise a simple and effective local a posteriori error estimate for partition of unity enriched finite element methods such as the extended finite element method (XFEM). In each element, the local estimator is the L2 norm of the difference between the raw XFEM strain field and an enhanced strain field computed by extended moving least squares (XMLS) derivative recovery obtained from the raw nodal XFEM displacements. The XMLS construction is tailored to the nature of the solution. The technique is applied to linear elastic fracture mechanics, in which near-tip asymptotic functions are added to the MLS basis. The XMLS shape functions are constructed from weight functions following the diffraction criterion to represent the discontinuity. The result is a very smooth enhanced strain solution including the singularity at the crack tip. Results are shown for two- and three-dimensional linear elastic fracture mechanics problems in mode I and mixed mode. The effectivity index of the estimator is close to 1 and improves upon mesh refinement for the studied near-tip problem. It is also shown that for the linear elastic fracture mechanics problems treated, the proposed estimator outperforms one of the superconvergent patch recovery technique of Zienkiewicz and Zhu, which is only C0. Parametric studies of the general performance of the estimator are also carried out. © 2007 Elsevier B.V. All rights reserved. [less ▲]