Spectral Analysis for Economic Time Series

The last ten years have witnessed an increasing interest of the econometrics community in spectral theory. In fact, decomposing the series evolution in periodic contributions allows a more insightful view of its structure and on its cyclical behavior at different time scales. In this paper I concisely broach the issues of cross-spectral analysis and filtering, dwelling in particular upon the windowed filter (Iacobucci and Noullez 2002). In order to show the usefulness of these tools, I present an application to real data, namely to US unemployment and inflation. I show how cross spectral analysis and filtering can be used to find correlation between them (i.e. the Phillips curve) in some specific frequency bands, even if it does not appear in raw data.spectral and cross spectral analysis, frequency selective filters, Phillips curve.

A Frequency-selective Filter for Short-Length Time Series

An effective and easy-to-implement frequency filter is designed by convolving a Hamming window with the ideal rectangular filter response function. Three other filters, Hodrick-Prescott, Baxter-King, and Christiano-Fitzgerald, are critically reviewed. The behavior of the Hamming-windowed filter is compared to the others through their frequency responses and their application to both an artificial, known-structure series and to the Euro zone quarterly GDP series. The Hamming-windowed filter has almost no leakage and is thus much better than the others in eliminating high-frequency components and has a significantly flatter bandpass response. Its low-frequency behavior demonstrates better removal of undesired long-term components. These improvements are particularly evident when working with short-length time series, such as are common in macroeconomics. The proposed filter is stationary, symmetric, uses all the information contained in the raw data, and stationarizes series integrated up to order two. It thus proves to be a good candidate for extracting frequency-defined business-cycle componentsspectral analysis, bandpass filtering

Entrepreneurship education in Italian universities: trend, situation and opportunities

The aim of this paper is to provide an analysis of the present situation and recent evolution in entrepreneurship courses and curricula in Italian universities. The analysis is based on a census of entrepreneurship courses and curricula run by Italian universities in 2004 and 2010. Entrepreneurship education in Italian universities is in its early development. Up to 2004 only a few universities had courses dedicated to entrepreneurship and the majority of them dealt with the development of the business plan. This situation has only slightly improved in the following years. Courses and curricula are mostly within business schools while very few exist in engineering and science schools. This situation contrasts with the need for entrepreneurship education in the Italian economy. Given the importance of traditional sectors in Italian industry we need to stimulate start-up in high-tech sectors: the development of entrepreneurship courses in engineering and in other science curricula could play an important role in this sense. At the same time we need to favor the growth process of small firms; this requires people who are able to play an entrepreneurial role in established firms.entrepreneurship education, university courses, intrapreneurship, entrepreneurial competences.

Nonequilibrium stationary state for a damped rotator

Perturbative construction of the nonequilibrium steady state of a rotator under a stochastic forcing while subject to torque and frictionComment: 18 page

On Particle Learning

This document is the aggregation of six discussions of Lopes et al. (2010) that we submitted to the proceedings of the Ninth Valencia Meeting, held in Benidorm, Spain, on June 3-8, 2010, in conjunction with Hedibert Lopes' talk at this meeting, and of a further discussion of the rejoinder by Lopes et al. (2010). The main point in those discussions is the potential for degeneracy in the particle learning methodology, related with the exponential forgetting of the past simulations. We illustrate in particular the resulting difficulties in the case of mixtures.Comment: 14 pages, 9 figures, discussions on the invited paper of Lopes, Carvalho, Johannes, and Polson, for the Ninth Valencia International Meeting on Bayesian Statistics, held in Benidorm, Spain, on June 3-8, 2010. To appear in Bayesian Statistics 9, Oxford University Press (except for the final discussion

Negative thermal conductivity of chains of rotors with mechanical forcing

We consider chains of rotors subjected to both thermal and mechanical forcings,in a nonequilibrium steady-state. Unusual nonlinear profiles of temperature and velocities are observed in the system. In particular, the temperature is maximal in the center, which is an indication of the nonlocal behavior of the system. In spite of that, local equilibrium holds for long enough chains. Our numerical results also show that, when the mechanical forcing is strong enough, the energy current can be increased by an inverse temperature gradient. This counterintuitive result again reveals the complexity of nonequilibrium states

Lack of kinase-independent activity of PI3Kγ in locus coeruleus induces ADHD symptoms through increased CREB signaling.

Although PI3Kγ has been extensively investigated in inflammatory and cardiovascular diseases, the exploration of its functions in the brain is just at dawning. It is known that PI3Kγ is present in neurons and that the lack of PI3Kγ in mice leads to impaired synaptic plasticity, suggestive of a role in behavioral flexibility. Several neuropsychiatric disorders, such as attention-deficit/hyperactivity disorder (ADHD), involve an impairment of behavioral flexibility. Here, we found a previously unreported expression of PI3Kγ throughout the noradrenergic neurons of the locus coeruleus (LC) in the brainstem, serving as a mechanism that regulates its activity of control on attention, locomotion and sociality. In particular, we show an unprecedented phenotype of PI3Kγ KO mice resembling ADHD symptoms. PI3Kγ KO mice exhibit deficits in the attentive and mnemonic domains, typical hyperactivity, as well as social dysfunctions. Moreover, we demonstrate that the ADHD phenotype depends on a dysregulation of CREB signaling exerted by a kinase-independent PI3Kγ-PDE4D interaction in the noradrenergic neurons of the locus coeruleus, thus uncovering new tools for mechanistic and therapeutic research in ADHD

Thermal conductivity of the Toda lattice with conservative noise

We study the thermal conductivity of the one dimensional Toda lattice perturbed by a stochastic dynamics preserving energy and momentum. The strength of the stochastic noise is controlled by a parameter $\gamma$. We show that heat transport is anomalous, and that the thermal conductivity diverges with the length $n$ of the chain according to $\kappa(n) \sim n^\alpha$, with $0 < \alpha \leq 1/2$. In particular, the ballistic heat conduction of the unperturbed Toda chain is destroyed. Besides, the exponent $\alpha$ of the divergence depends on $\gamma$