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.

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.

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.

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.

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

Symmetry relation for multifractal spectra at random critical points

Random critical points are generically characterized by multifractal properties. In the field of Anderson localization, Mirlin, Fyodorov, Mildenberger and Evers [Phys. Rev. Lett 97, 046803 (2006)] have proposed that the singularity spectrum $f(\alpha)$ of eigenfunctions satisfies the exact symmetry $f(2d-\alpha)=f(\alpha)+d-\alpha$ at any Anderson transition. In the present paper, we analyse the physical origin of this symmetry in relation with the Gallavotti-Cohen fluctuation relations of large deviation functions that are well-known in the field of non-equilibrium dynamics: the multifractal spectrum of the disordered model corresponds to the large deviation function of the rescaling exponent $\gamma=(\alpha-d)$ along a renormalization trajectory in the effective time $t=\ln L$. We conclude that the symmetry discovered on the specific example of Anderson transitions should actually be satisfied at many other random critical points after an appropriate translation. For many-body random phase transitions, where the critical properties are usually analyzed in terms of the multifractal spectrum $H(a)$ and of the moments exponents X(N) of two-point correlation function [A. Ludwig, Nucl. Phys. B330, 639 (1990)], the symmetry becomes $H(2X(1) -a)= H(a) + a-X(1)$, or equivalently $\Delta(N)=\Delta(1-N)$ for the anomalous parts $\Delta(N) \equiv X(N)-NX(1)$. We present numerical tests in favor of this symmetry for the 2D random $Q-$state Potts model with various $Q$.Comment: 15 pages, 3 figures, v2=final versio

Mobility and Diffusion of a Tagged Particle in a Driven Colloidal Suspension

We study numerically the influence of density and strain rate on the diffusion and mobility of a single tagged particle in a sheared colloidal suspension. We determine independently the time-dependent velocity autocorrelation functions and, through a novel method, the response functions with respect to a small force. While both the diffusion coefficient and the mobility depend on the strain rate the latter exhibits a rather weak dependency. Somewhat surprisingly, we find that the initial decay of response and correlation functions coincide, allowing for an interpretation in terms of an 'effective temperature'. Such a phenomenological effective temperature recovers the Einstein relation in nonequilibrium. We show that our data is well described by two expansions to lowest order in the strain rate.Comment: submitted to EP

Large-q asymptotics of the random bond Potts model

We numerically examine the large-q asymptotics of the q-state random bond Potts model. Special attention is paid to the parametrisation of the critical line, which is determined by combining the loop representation of the transfer matrix with Zamolodchikov's c-theorem. Asymptotically the central charge seems to behave like c(q) = 1/2 log_2(q) + O(1). Very accurate values of the bulk magnetic exponent x_1 are then extracted by performing Monte Carlo simulations directly at the critical point. As q -> infinity, these seem to tend to a non-trivial limit, x_1 -> 0.192 +- 0.002.Comment: 9 pages, no figure

Critical Behavior and Lack of Self Averaging in the Dynamics of the Random Potts Model in Two Dimensions

We study the dynamics of the q-state random bond Potts ferromagnet on the square lattice at its critical point by Monte Carlo simulations with single spin-flip dynamics. We concentrate on q=3 and q=24 and find, in both cases, conventional, rather than activated, dynamics. We also look at the distribution of relaxation times among different samples, finding different results for the two q values. For q=3 the relative variance of the relaxation time tau at the critical point is finite. However, for q=24 this appears to diverge in the thermodynamic limit and it is ln(tau) which has a finite relative variance. We speculate that this difference occurs because the transition of the corresponding pure system is second order for q=3 but first order for q=24.Comment: 9 pages, 13 figures, final published versio

Digital videodensitometric measurement of aortic regurgitation

A videodensitometric method for quantification of aortic regurgitation which requires neither measurement of cardiac output nor determination of enddiastolic and endsystolic left ventricular volumes has been developed. The injection of 20 ml of contrast medium into the left ventricle is digitally recorded at 25 images s−1 during 20 s using an equipment for digital subtraction angiography (Digitron 2, Siemens). The Digitron computes 2 ‘time dilution curves' (TDC) from the unsubtracted image sequence, for 2 regions of interest drawn around the angiographic enddiastolic and endsystolic left ventricular silhouettes. Enddiastolic and endsystolic points of the TDC are then entered into a VAX-750 computer, which calculates the ejection fraction (EF), the forward ejection fraction (FEF) and the regurgitant fraction (RGF). This is performed by a complex fitting algorithm based on a physical model of the washout process of contrast medium, which reconstructs the two best enddiastolic and endsystolic baselines in the washout parts of the two TDC. The EF, FEF and RGF obtained in 9 regurgitant and 11 nonregurgitant patients have been compared with the corresponding values EFv, FEFv and RGFv obtained by a conventional technique (Cardiogreen and biplane LV area-length volumetry). Regression analysis yielded: EF = 0.88 × EFv (regression line forced through the origin), r = 0.77, FEF = 0.76 × FEFv + 3, r = 0.96, RGF = 0.94 × RGFv + 5, r = 0.98 (v stands for volumetry