On monopolistic competition and optimal product diversity: workers' rents also matter

in Canadian Journal of Economics (2009), 42(4), 1347-1360

In the Dixit-Stiglitz model of monopolistic competition, entry of rms is socially too small. Other authors have shown that excess entry is also a possibility with other preferences for diversity. We show ... [more ▼]

In the Dixit-Stiglitz model of monopolistic competition, entry of rms is socially too small. Other authors have shown that excess entry is also a possibility with other preferences for diversity. We show that workers rents also contribute to explain excess entry through a general equilibrium mechanism. Larger wages indeed raises the aggregate earnings and rms sales and pro ts, which entices too many rms to enter. We discuss the possibility of over-provision of varieties by comparing the equilibrium to unconstrained and constrained social optima and to other regulatory framework where wages are not controlled. [less ▲]

Joint Bit Allocation and Precoding for MIMO Systems with Decision Feedback Detection

in IEEE Transactions on Signal Processing (2009), 57(11), 4509-4521

This paper considers the joint design of bit loading, precoding and receive filters for a multiple-input multiple-output (MIMO) digital communication system employing decision feedback (DF) detection at ... [more ▼]

This paper considers the joint design of bit loading, precoding and receive filters for a multiple-input multiple-output (MIMO) digital communication system employing decision feedback (DF) detection at the receiver. Both the transmitter as well as the receiver are assumed to know the channel matrix perfectly. It is well known that, for linear MIMO transceivers, a diagonal transmission (i.e., orthogonalization of the channel matrix) is optimal for some criteria. Surprisingly, it was shown five years ago that for the family of Schur-convex functions an additional rotation of the symbols is necessary. However, if the bit loading is optimized jointly with the linear transceiver, then this rotation is unnecessary. Similarly, for DF MIMO optimized transceivers a rotation of the symbols is sometimes needed. The main result of this paper shows that for a DF MIMO transceiver where the bit loading is jointly optimized with the transceiver filters, the rotation of the symbols becomes unnecessary, and because of this, also the DF part of the receiver is not required. The proof is based on a relaxation of the available bit rates on the individual substreams to the set of positive real numbers. In practice, the signal constellations are discrete and the optimal relaxed bit loading has to be rounded. It is shown that the loss due to rounding is small, and an upper bound on the maximum loss is derived. Numerical results are presented that confirm the theoretical results and demonstrate that orthogonal transmission and the truly optimal DF design perform almost equally well. [less ▲]

Banning solves the problem? Effects of banning mobile phone use in schools on cyber bullying

Poster (2009, November)

Obligations d'information des sociétés cotées en droit communautaire

Doctoral thesis (2009)

La stylistique : une discipline à l’aune de la vie

Presentation (2009, October 27)

Le Laboratoire Souterrain de Géodynamique de Walferdange - Un joyau pour les sciences de la terre

Speeches/Talks (2009)

La théorie rawlsienne de la justice et les relations internationales

Doctoral thesis (2009)

Working memory and language learning: A 4-year longitudinal study

Poster (2009, October)

The aim of the present study was to investigate the contribution of two working memory systems (the phonological loop and the central executive) to children’s foreign language learning. A sample of 119 ... [more ▼]

The aim of the present study was to investigate the contribution of two working memory systems (the phonological loop and the central executive) to children’s foreign language learning. A sample of 119 Luxembourgish children, whose native language is Luxembourgish and who learn German and French as secondary languages in school were assessed longitudinally over a 4-year time period. Children were tested in kindergarten (5 years of age), in first, second, and third grade with a one-year interval between each testing wave. Results indicate that individual differences in phonological loop functioning were causally related to foreign vocabulary development. One particular phonological loop measure - the repetition of low wordlike nonwords - was identified as the single best predictor of the acquisition of an unfamiliar foreign language up to two years later, suggesting that this measure may provide a valuable tool for early screening to identify children who are at present and future risk for foreign language learning difficulties. [less ▲]

Association between goal orientation and the means as well as the outcomes of a goal

Poster (2009, October)

Axiomatizations of quasi-polynomial functions on bounded chains

in Aequationes Mathematicae (2009), 78(1-2), 195-213

Two emergent properties in aggregation theory are investigated, namely horizontal maxitivity and comonotonic maxitivity (as well as their dual counterparts) which are commonly defined by means of certain ... [more ▼]

Two emergent properties in aggregation theory are investigated, namely horizontal maxitivity and comonotonic maxitivity (as well as their dual counterparts) which are commonly defined by means of certain functional equations. We completely describe the function classes axiomatized by each of these properties, up to weak versions of monotonicity in the cases of horizontal maxitivity and minitivity. While studying the classes axiomatized by combinations of these properties, we introduce the concept of quasi-polynomial function which appears as a natural extension of the well-established notion of polynomial function. We give further axiomatizations for this class both in terms of functional equations and natural relaxations of homogeneity and median decomposability. As noteworthy particular cases, we investigate those subclasses of quasi-term functions and quasi-weighted maximum and minimum functions, and provide characterizations accordingly. [less ▲]