Couts et benefices du passage d'une faible inflation a la stabilite des prix. Une comparaison internationale.

Cet article évalue, en reprenant l'approche de Feldstein [1996], quelques-uns des coûts et des bénéfices du passage d'une faible inflation (2%) à une inflation nulle pour les économies française, allemande, britannique, espagnole et américaine. Cette approche met l'accent sur les distorsions dans les décisions d'épargne et d'investissement en logement engendrées par l'indexation imparfaite du système fiscal. Des études récentes ont montré qu'un passage d'une inflation de 2% à la stabilité des prix conduisait à des gains en surplus des ménages de l'ordre de 1,05% du PIB par an aux Etats-Unis, de 1,4% en Allemagne, de 1,7% en Espagne et de seulement 0,21% au Royaume-Uni. Nous montrons que ces différences d'évaluation relèvent en grande partie du choix de l'élasticité de l'épargne au taux d'intérêt et de spécificités de la fiscalité de ces pays. En France, sur la base de la fiscalité de l'épargne prévalant en 1998, le bénéfice annuel du retour observé à la stabilité des prix serait de 0,66%.Inflation ; prix ; cycles economiques.

Green Function Simulation of Hamiltonian Lattice Models with Stochastic Reconfiguration

We apply a recently proposed Green Function Monte Carlo to the study of Hamiltonian lattice gauge theories. This class of algorithms computes quantum vacuum expectation values by averaging over a set of suitable weighted random walkers. By means of a procedure called Stochastic Reconfiguration the long standing problem of keeping fixed the walker population without a priori knowledge on the ground state is completely solved. In the $U(1)_2$ model, which we choose as our theoretical laboratory, we evaluate the mean plaquette and the vacuum energy per plaquette. We find good agreement with previous works using model dependent guiding functions for the random walkers.Comment: 14 pages, 5 PostScript Figures, RevTeX, two references adde

Historical and interpretative aspects of quantum mechanics: a physicists' naive approach

Many theoretical predictions derived from quantum mechanics have been confirmed experimentally during the last 80 years. However, interpretative aspects have long been subject to debate. Among them, the question of the existence of hidden variables is still open. We review these questions, paying special attention to historical aspects, and argue that one may definitively exclude local realism on the basis of present experimental outcomes. Other interpretations of Quantum Mechanics are nevertheless not excluded.Comment: 30 page

Probability distributions for polymer translocation

We study the passage (translocation) of a self-avoiding polymer through a membrane pore in two dimensions. In particular, we numerically measure the probability distribution Q(T) of the translocation time T, and the distribution P(s,t) of the translocation coordinate s at various times t. When scaled with the mean translocation time , Q(T) becomes independent of polymer length, and decays exponentially for large T. The probability P(s,t) is well described by a Gaussian at short times, with a variance that grows sub-diffusively as t^{\alpha} with \alpha~0.8. For times exceeding , P(s,t) of the polymers that have not yet finished their translocation has a non-trivial stable shape.Comment: 5 pages, 4 figure

Firm Investment and Monetary Policy Transmission in the Euro Area.

We present a comparable set of results on the monetary transmission channels on firm investment for the four largest euro-area countries (Germany, France, Italy and Spain). With particularly rich micro datasets for each country containing over 215,000 observations from 1985 to 1999, we ex-plore what can be learned about the interest channel and the broad credit channel. For each of those countries, we estimate neo-classical investment relationships, explaining investment by its user cost, sales and cash flow. We find investment to be sensitive to user cost changes in all those four countries. This implies an operative interest channel in these euro-area countries. We also find in-vestment in all countries to be quite sensitive to cash flow movements. However, only in Italy do smaller firms react more to cash flow movements than large firms, implying that a broad credit channel might not be equally pervasive in all countries.Investment, Monetary transmission channels, User cost of capital.

Pitfalls in Investment Euler Equations.

This paper investigates three pitfalls concerning the test of the Euler equation facing quadratic adjustment costs and perfect capital markets on a large balanced panel data of 4025 french firms. First, the quadratic parameterization of adjustment costs is too restrictive, and power series approximations of adjustment costs are tested. Second, we isolate firms whose optimal Euler condition is not altered even in the presence of fixed adjustment costs. Third, we identify instruments which contribute to model failure via standard GMM\ tests. These methods point that financial instruments contribute to reject strongly the standard model, which shows that it is misspecified.Investment ; adjustment costs ; financial constraints ; generalized method of moments.

Optimal Capacity in the Banking Sector and Economic Growth.

The paper investigates, from the welfare and growth point of view, the determination of the optimal capacity of the banking system. For that purpose, we consider an overlapping generation model with endogenous growth. There is horizontal differentiation and imperfect competition in the banking sector. Macroeconomic shocks affect the return on capital and, together with the expectations of depositors, condition the stability of the banking sector. We specify to what extent deposit insurance may reduce instability and increase the number of deposits, welfare and growth. We also characterize the conditions under which excess banking capacities may appear and how their reduction may improve welfare.Deposit insurance ; imperfect ; competition ; growth, banking.

Critical Behavior of the Random Potts Chain

We study the critical behavior of the random q-state Potts quantum chain by density matrix renormalization techniques. Critical exponents are calculated by scaling analysis of finite lattice data of short chains ($L \leq 16$) averaging over all possible realizations of disorder configurations chosen according to a binary distribution. Our numerical results show that the critical properties of the model are independent of q in agreement with a renormalization group analysis of Senthil and Majumdar (Phys. Rev. Lett.{\bf 76}, 3001 (1996)). We show how an accurate analysis of moments of the distribution of magnetizations allows a precise determination of critical exponents, circumventing some problems related to binary disorder. Multiscaling properties of the model and dynamical correlation functions are also investigated.Comment: LaTeX2e file with Revtex, 9 pages, 8 eps figures, 4 tables; typos correcte