Some linear Jacobi structures on vector bundles

We study Jacobi structures on the dual bundle $A^\ast$ to a vector bundle $A$ such that the Jacobi bracket of linear functions is again linear and the Jacobi bracket of a linear function and the constant function 1 is a basic function. We prove that a Lie algebroid structure on $A$ and a 1-cocycle $\phi \in \Gamma (A^\ast)$ induce a Jacobi structure on $A^\ast$ satisfying the above conditions. Moreover, we show that this correspondence is a bijection. Finally, we discuss some examples and applications.Comment: 6 pages, To appear in C. R. Acad. Sci. Paris, S\'erie

Unemployment and Inflation Persistence in Spain: Are There Phillips Trade-Offs?

This paper studies the dynamic behavior of inflation and unemployment in Spain during the period 1964?1997. In particular, we analyze the implications of high persistence in both unemployment and inflation dynamics for inference regarding the size of Phillips trade-offs and sacrifice ratios in the Spanish economy, in response to a demand shock. To do so we use a Stuctural VAR approach with several identification outlines which give rise to alternative interpretations of the joint unemployment-inflation dynamics. When using a bivariate VAR we cannot reject the existence of a permanent output loss of one-half of one percentage point for each percentage point of permanent disinflation. However, when the VAR is augmented with a third variable, in order to disentangle monetary from non-monetary shocks within the demand class, the evidence favours a lower and marginally permanent trade-off with an output loss of about one-fourth of one percentage point.Publicad

Uncertainty in conflicts

This paper theoretically assesses the role that uncertainty plays in the intensity of conflicts. The standard two-player rent-seeking contest model (Tullock, 1980) is extended to allow for privately known subjective values of the prize. The conflict is modeled as a Bayesian game on which each player´s valuation is drawn independently from arbitrary distributions. We find sufficient conditions for when first-order and second-order stochastic refinements in the distributions cause predictable movements in the conflict´s dissipation. We focus on arbitrary contest success functions and arbitrary independent distributions for each player, allowing us to extend our analysis beyond the case of symmetric equilibria.conflict, uncertainty, monotone comparative statics, Bayesian games

Multiple policymakers and the social value of public information

In most economies, macroeconomic policy is conducted by two or more independent authorities. In general, each policymaker has a different piece of information about the state of the economy, and this information is different from the one held by the private sector. We extend the model of James and Lawler [2011], of asymmetric and imperfect information, to account for the existence of two independent policymakers. The active policymakers can choose optimally what policy rule to follow, what information to share with the other policymakers, and what information to share with the public. This paper studies the social value of public information when the policymakers are active. We find that improving the quality of the signals transmitted to the private sector can increase the expected value of welfare. If both policymakers seek to maximize expected welfare, full information sharing between authorities achieves higher expected welfare than no information sharing at all.Macroeconomic Policy, Asymmetric Information, Policy Coordination. Classification JEL: D82, D83, E52, E61, E62.

Thermodynamics of Coarse Grained Models of Super-Cooled Liquids

In recent papers, we have argued that kinetically constrained coarse grained models can be applied to understand dynamic properties of glass forming materials, and we have used this approach in various applications that appear to validate this view. In one such paper [J.P. Garrahan and D. Chandler, Proc. Nat. Acad. Sci. USA 100, 9710 (2003)], among other things we argued that this approach also explains why the heat capacity discontinuity at the glass transition is generally larger for fragile materials than for strong materials. In the preceding article, Biroli, Bouchaud and Tarjus (BB&T) [cond-mat/0412024] have objected to our explanation on this point, arguing that the class of models we apply is inconsistent with both the absolute size and temperature dependence of the experimental specific heat. Their argument, however, neglects parameters associated with the coarse graining. Accounting for these parameters, we show here that our treatment of dynamics is not inconsistent with heat capacity discontinuities.Comment: 5 pages, 2 figures. Revised version to appear in J. Chem. Phy

In Search of the "Bank Lending Channel": Causality Analysis for the Transmission Mechanism of U.S. Monetary Policy

The bank lending channel states that changes in monetary policy cause changes in bank loans thus causing changes in real income. This implies the Federal Reserve can influence real income by controlling the level of intermediated loans. We apply a new method to test for an operative bank lending channel in the transmission mechanism of monetary policy. Combining an error correction model with directed acyclic graphs, we explore the existence of a bank lending channel and the effectiveness of U.S. monetary policy since 1960. This paper shows when an operative bank lending channel existed, explains its impact, and evaluates other channels of monetary policy.Financial Economics,