Cooperative heterogeneous facilitation: multiple glassy states and glass-glass transition

The formal structure of glass singularities in the mode-coupling theory (MCT) of supercooled liquids dynamics is closely related to that appearing in the analysis of heterogeneous bootstrap percolation on Bethe lattices, random graphs and complex networks. Starting from this observation one can build up microscopic on lattice realizations of schematic MCT based on cooperative facilitated spin mixtures. I discuss a microscopic implementation of the F13 schematic model including multiple glassy states and the glass-glass transition. Results suggest that our approach is flexible enough to bridge alternative theoretical descriptions of glassy matter based on the notions of quenched disorder and dynamic facilitation.Comment: 4 pages, 2 figure

Effects of a trapped vortex cell on thick wing profile

Experimental investigation on the effects originated from a trapped vortex cell on the NACA0024 airfoi

INFLATION TARGETING AND THE FULL EMPLOYMENT OBJECTIVE

This paper shows the equivalence between various ways of stating the inflation objective. Defining a target range and the percentage of the time it is hoped to fall within its borders is tantamount to defining a target for projected inflation over a given horizon. Both versions are similar to defining the goal in terms of expected value and the desired variance for the inflationary trend. The paper also shows that the tolerance to inflation deviations from the target—directly associated to the policy horizon—depends on the costs of inflation deviating from the target as well as on the deviations of output from its full-employment potential. Therefore, stating the target as a function of an inflation objective does not overlook the importance of unemployment or the output gap in monetary policy decisions.

Money and Inflation: Where do we Stand?

This article analyzes the rapid growth of money (M1A) in the Chilean economy, that has coincided with low inflation and a loosened monetary policy. This has been advocated to assert that such monetary growth is inconsistent with the inflation target. This work is intended to prove such an argument wrong. First, episodes occurred in other lower-inflation countries are presented, where monetary aggregates have grown even faster than in Chile, without resulting in higher inflation. Second, money trends are shown to be consistent with money demand estimates, although these are very volatile. Finally, the paper explains why in the context of a monetary policy based on inflation targeting, where the policy instrument is the interest rate, it is possible for money to fluctuate widely without jeopardizing the inflation target. Even if inflation is associated to an excessive increase in the amount of money, and monetary policy is neutral over the long term, monetary aggregates provide little information on inflationary pressures.

Fear of Floating and Exchange Rate Policy in Chile

The paper reviews the exchange rate management experience in Chile, with particular emphasis on the floating exchange rate regime implemented in 1999 and its two forex intervention episodes. It presents evidence on Chile’s favorable conditions to deal with exchange rate shocks: a well-developed financial sector, that offers hedging opportunities taken up by the corporate sector to decrease its vulnerability through balance sheet effects; and a low and decreasing level of passthrough from the exchange rate to prices. These elements contribute to diminish the costs of the floating exchange rate regime, reducing its implied financial and price instability threat, and therefore avoiding fear of floating. Moreover, it provides enough credibility to the current exchange rate system, reinforcing the commitment to making interventions a rare event.

On random flights with non-uniformly distributed directions

This paper deals with a new class of random flights $\underline{\bf X}_d(t),t>0,$ defined in the real space $\mathbb{R}^d, d\geq 2,$ characterized by non-uniform probability distributions on the multidimensional sphere. These random motions differ from similar models appeared in literature which take directions according to the uniform law. The family of angular probability distributions introduced in this paper depends on a parameter $\nu\geq 0$ which gives the level of drift of the motion. Furthermore, we assume that the number of changes of direction performed by the random flight is fixed. The time lengths between two consecutive changes of orientation have joint probability distribution given by a Dirichlet density function. The analysis of $\underline{\bf X}_d(t),t>0,$ is not an easy task, because it involves the calculation of integrals which are not always solvable. Therefore, we analyze the random flight $\underline{\bf X}_m^d(t),t>0,$ obtained as projection onto the lower spaces $\mathbb{R}^m,m<d,$ of the original random motion in $\mathbb{R}^d$. Then we get the probability distribution of $\underline{\bf X}_m^d(t),t>0.$ Although, in its general framework, the analysis of $\underline{\bf X}_d(t),t>0,$ is very complicated, for some values of $\nu$, we can provide some results on the process. Indeed, for $\nu=1$, we obtain the characteristic function of the random flight moving in $\mathbb{R}^d$. Furthermore, by inverting the characteristic function, we are able to give the analytic form (up to some constants) of the probability distribution of $\underline{\bf X}_d(t),t>0.$Comment: 28 pages, 3 figure

A generalized least squares estimation method for VARMA models. (Revised edition).

In this paper a new generalized least squares procedure for estimating VARMA models is proposed. This method differs from existing ones in explicitly considering the stochastic structure of the approximation error that arises when lagged innovations are replaced with lagged residuals obtained from a long VAR. Simulation results indicate that this method improves the accuracy of estimates with small and moderate sample sizes, and increases the frequency of identifying small nonzero parameters, with respect to both Double Regression and exact maximum likelihood estimation procedures