Congruences for L-functions of additive exponential sums

We give a congruence for L-functions coming from affine additive exponential sums over a finite field. Precisely, we give a congruence for certain operators coming from Dwork's theory. This congruence is very similar to the congruence of Manin for the characteristic polynomial of the action of Frobenius on the Jacobian of a curve defined over a finite field.Comment: This paper generalizes and extends the results in the previous paper arXiv:0912.205

The effect of colored noise on heteroclinic orbits

The dynamics of a weakly dissipative Hamiltonian system submitted to stochastic perturbations has been investigated by means of asymptotic methods. The probability of noise-induced separatrix crossing, which drastically changes the fate of the system, is derived analytically in the case where noise is an additive Kubo-Anderson process. This theory shows how the geometry of the separatrix, as well as the noise intensity and correlation time, affect the statistics of crossing. Results can be applied to a wide variety of systems, and are valid in the limit where the noise correlation time scale is much smaller than the time scale of the undisturbed Hamiltonian dynamics

A Smoke Screen Theory of Financial Intermediation

This paper analyzes a stylized (two period) credit market where investors care about the appropriability of the information they produce when they engage in costly ex ante evaluation of borrowers quality. We show that diversified intermediation arises as a dissimulation mechanism allowing investors to extract informational rents in the second period, thereby mitigating the underlying appropriability problem.Financial intermediation ; informational rent ; asymmetric information ; free riding ; diversification

On damping created by heterogeneous yielding in the numerical analysis of nonlinear reinforced concrete frame elements

In the dynamic analysis of structural engineering systems, it is common practice to introduce damping models to reproduce experimentally observed features. These models, for instance Rayleigh damping, account for the damping sources in the system altogether and often lack physical basis. We report on an alternative path for reproducing damping coming from material nonlinear response through the consideration of the heterogeneous character of material mechanical properties. The parameterization of that heterogeneity is performed through a stochastic model. It is shown that such a variability creates the patterns in the concrete cyclic response that are classically regarded as source of damping

The Shimer Puzzle and the Correct Identification of Productivity Shocks

Shimer (2005a) claims that the Mortensen-Pissarides search model of unemployment lacks an ampiflication mechanism because it cannot generate the observed business cycle fluctuations in unemployment given labor productivity shocks of plausible magnitude. This paper argues that part of the problem lies with the correct identification of productivity shocks. Because of the endogeneity of measured labor productivity, filtering out the trend component as in Shimer (2005a) may not correctly identify the shocks driving unemployment. Using a New- Keynesian framework with search unemployment, this paper estimates that close to 50% of the Shimer puzzle is due to the misidentification of productivity shocks. In addition, I show that extending the search model with an aggregate demand side remarkably improves the ability of the standard search model to match the moments of key labor market variables.unemployment fluctuations, labor productivity, search and matching model, New-Keynesian model

Dynamic pricing rule and R&D

This article models the intertemporal behaviour of a firm that sets product prices and simultaneously invests in R&D. The model shows that the dynamic pricing rule follows the evolution of the production cost and is independent of the evolution of the product quality. Thus, process innovation, which reduces production cost, is the main determinant of a firm's pricing policy over time. Moreover, the firm invests more in process innovation over time at the expense of product innovation. Hence, the model explains the decrease in the cost of production and in the price of technological products throughout their life cycle.Dynamic pricing, R&D, optimal control

Measure rigidity for leafwise weakly rigid actions

In this paper, given a Borel action $G\curvearrowright X$, we introduce a new approach to obtain classification of conditional measures along a $G$-invariant foliation along which $G$ has a controlled behavior. Given a Borel action $G\curvearrowright X$ over a Lebesgue space $X$ we show that if $G\curvearrowright X$ preserves an invariant system of metrics along a Borel lamination $\mathcal F$, which satisfy a good packing estimative hypothesis, then the ergodic measures preserved by the action are rigid in the sense that the system of conditional measures with respect to the partition $\mathcal F$ are the Hausdorff measures given by the metric system or are supported in a countable number of boundaries of balls. The argument we employ does not require any structure on $G$ other then second-countability and no hyperbolicity on the action as well. Our main result is interesting on its own, but to exemplify its strength and usefulness we show some applications in the context of cocycles over hyperbolic maps and to certain partially hyperbolic maps