Estimating the Costs and Benefits of EMU: The Impact of External Shocks on Labour Markets

Discussions of the economic costs and benefits of EMU usually take as their basis the optimum currency area (OCA) approach. This approach starts from the premise that when an external shock hits the economy, it is easier to adjust the exchange rate than domestic prices or wages. Most economists accept the general idea behind this approach, namely that nominal wages are usually sticky in the shortrun and that it is therefore easier to adjust to external shocks and obtain changes in the real exchange rate or the terms of trade through a movement in the exchange rate. But there is little agreement on how important these "external" shocks are in reality. We try to measure the importance of external shocks for (un)employment. We find that external shocks have little impact on unemployment, but are more important in the evolution of employment in manufacturing. The results differ, however, strongly from country to country and for about half of EU member countries we did not find any significant relationship. Taking into account various potential shock absorbers (exchange rate movements, fiscal and monetary policy) does not affect the results. We conclude that the loss of the exchange rate instrument will not lead to massive unemployment problems.exchange rates;export demand;external shocks;optimal currency area;(un)employment

Control of the finite size corrections in exact diagonalization studies

We study the possibility of controlling the finite size corrections in exact diagonalization studies quantitatively. We consider the one- and two dimensional Hubbard model. We show that the finite-size corrections can be be reduced systematically by a grand-canonical integration over boundary conditions. We find, in general, an improvement of one order of magnitude with respect to studies with periodic boundary conditions only. We present results for ground-state properties of the 2D Hubbard model and an evaluation of the specific heat for the 1D and 2D Hubbard model.Comment: Phys. Rev. B (Brief Report), in pres

Vertex routing models

A class of models describing the flow of information within networks via routing processes is proposed and investigated, concentrating on the effects of memory traces on the global properties. The long-term flow of information is governed by cyclic attractors, allowing to define a measure for the information centrality of a vertex given by the number of attractors passing through this vertex. We find the number of vertices having a non-zero information centrality to be extensive/sub-extensive for models with/without a memory trace in the thermodynamic limit. We evaluate the distribution of the number of cycles, of the cycle length and of the maximal basins of attraction, finding a complete scaling collapse in the thermodynamic limit for the latter. Possible implications of our results on the information flow in social networks are discussed.Comment: 12 pages, 6 figure

Real time localization of Gamma Ray Bursts with INTEGRAL

The INTEGRAL satellite has been successfully launched in October 2002 and has recently started its operational phase. The INTEGRAL Burst Alert System (IBAS) will distribute in real time the coordinates of the GRBs detected with INTEGRAL. After a brief introduction on the INTEGRAL instruments, we describe the main IBAS characteristics and report on the initial results. During the initial performance and verification phase of the INTEGRAL mission, which lasted about two months, two GRBs have been localized with accuracy of about 2-4 arcmin. These observations have allowed us to validate the IBAS software, which is now expected to provide quick (few seconds delay) and precise (few arcmin) localization for about 10-15 GRBs per year.Comment: 6 pages, latex, 3 figures, submitted to Adv. Sp. Res., Proceedings of the 34th COSPAR Scientific Assembly, Houston, 10-19 October 200

Attractor Metadynamics in Adapting Neural Networks

Slow adaption processes, like synaptic and intrinsic plasticity, abound in the brain and shape the landscape for the neural dynamics occurring on substantially faster timescales. At any given time the network is characterized by a set of internal parameters, which are adapting continuously, albeit slowly. This set of parameters defines the number and the location of the respective adiabatic attractors. The slow evolution of network parameters hence induces an evolving attractor landscape, a process which we term attractor metadynamics. We study the nature of the metadynamics of the attractor landscape for several continuous-time autonomous model networks. We find both first- and second-order changes in the location of adiabatic attractors and argue that the study of the continuously evolving attractor landscape constitutes a powerful tool for understanding the overall development of the neural dynamics

Synthesis and Properties of Dipyridylcyclopentenes

A short and general route to the substituted dipyridylcyclopentenes was explored and several new compounds belonging to this new group of diarylethenes were synthesized. The study of their photochromic and thermochromic properties shows that the rate of the thermal ring opening is strongly dependent on the polarity of the solvent.

Stability of Inhomogeneous Superstructures from Renormalized Mean-field Theory of the t--J Model

Using the t--J model (which can also include Coulomb repulsion) and the ``plain vanilla'' renormalized mean-field theory of Zhang et al. (1988), stability of inhomogeneous 4a x 4a superstructures as those observed in cuprates superconductors around hole doping 1/8 is investigated. We find a non-uniform 4a x 4a bond order wave involving simultaneously small (~ 10^-2 t) inhomogeneous staggered plaquette currents as well as a small charge density modulation similar to pair density wave order. On the other hand, no supersolid phase involving a decoupling in the superconducting particle-particle channel is found.Comment: 4 page