An Indicator Based on Revisions in the French Investment Survey: A Useful Tool for Forecasting Business Investments

The quarterly survey of investments in industry conducted by INSEE is a prime source of information concerning short-term economic changes in productive investment. The annual nature of the questions asked makes it difficult for them to be used in forecasting on a quarterly basis. For that reason, this article suggests a quarterly indicator of revisions in industrial firms anticipated investments. This indicator measures adjustments to investment projects throughout the year, based on short-term economic changes. Being closely correlated to quarterly changes in corporate investment, it is available around three months before the publication of the initial quarterly national accounts figures. The distributions examined do not verify certain characteristics of normal distribution. Therefore, it is necessary to apply an estimation method which is robust to the revisions of outliers. Also taking into account the presence of heteroscedasticity, the method known as "Quasi-generalised M-estimators" was applied.Investment, Business Tendency Surveys, Outliers, Quasi-Generalized M-Estimators

Extended Edge States in Finite Hall Systems

We study edge states of a random Schroedinger operator for an electron submitted to a magnetic field in a finite macroscopic two dimensional system of linear dimensions equal to L. The y direction is L-periodic and in the x direction the electron is confined by two smoothly increasing parallel boundary potentials. We prove that, with large probability, for an energy range in the first spectral gap of the bulk Hamiltonian, the spectrum of the full Hamiltonian consists only on two sets of eigenenergies whose eigenfuntions have average velocities which are strictly positive/negative, uniformly with respect to the size of the system. Our result gives a well defined meaning to the notion of edge states for a finite cylinder with two boundaries, and extends previous studies on systems with only one boundary.Comment: 24 pages, 1 figure; Submitte

Entropic and gradient flow formulations for nonlinear diffusion

Nonlinear diffusion $\partial_t \rho = \Delta(\Phi(\rho))$ is considered for a class of nonlinearities $\Phi$. It is shown that for suitable choices of $\Phi$, an associated Lyapunov functional can be interpreted as thermodynamics entropy. This information is used to derive an associated metric, here called thermodynamic metric. The analysis is confined to nonlinear diffusion obtainable as hydrodynamic limit of a zero range process. The thermodynamic setting is linked to a large deviation principle for the underlying zero range process and the corresponding equation of fluctuating hydrodynamics. For the latter connections, the thermodynamic metric plays a central role

On-pump beating heart coronary surgery for high risk patients requiring emergency multiple coronary artery bypass grafting

BACKGROUND: Cardiopulmonary bypass (CPB) with aortic cross-clamping and cardioplegic arrest remains the method of choice for patients requiring standard myocardial revascularization. Therefore, very high-risk patients presenting with acute coronary syndrome, unstable angina, onset of cardiac decompensation and requiring emergency multiple myocardial revascularization, can have a poor outcome. The on-pump beating heart technique can reduce the mortality and the morbidity in such a selected group of patients and this report describes our clinical experience. METHODS: Out of 290 patients operated for CABG from January 2005 to January 2006, 25 (8.6%) selected high-risk patients suffering from life threatening coronary syndrome (mean age 69 +/- 7 years) and requiring emergency multiple myocardial revascularization, underwent on-pump beating heart surgery. The mean pre-operative left ventricle ejection fraction (LVEF) was 27 +/- 8%. The majority of them (88%) suffered of tri-vessel coronary disease and 6 (24%) had a left main stump disease. Nine patients (35%) were on severe cardiac failure and seven among them (28%) received a pre-operative intra-aortic balloon pump. The pre-operative EuroScore rate was equal or above 8 in 18 patients (73%). RESULTS: All patients underwent on-pump-beating heart coronary revascularization. The mean number of graft/patient was 2.9 +/- 0.6 and the internal mammary artery was used in 23 patients (92%). The mean CPB time was 84 +/- 19 minutes. Two patients died during the recovery stay in the intensive care unit, and there were no postoperative myocardial infarctions between the survivors. Eight patients suffered of transitorily renal failure and 1 patient developed a sternal wound infection. The mean hospital stay was 12 +/- 7 days. The follow-up was complete for all 23 patients survived at surgery and the mean follow-up time was 14 +/- 5 months. One patient died during the follow-up for cardiac arrest and 2 patients required an implantable cardiac defibrillator. One year after surgery they all had a standard trans-thoracic echocardiogram showing a mean LVEF rate of 36 +/- 11.8%. CONCLUSION: Standard on-pump arrested heart coronary surgery has higher mortality and morbidity in emergencies. The on-pump beating heart myocardial revascularization seems to be a valid alternative for the restricted and selected cohort of patients suffering from life threatening coronary syndrome and requiring multiple emergency CABG

Intermixture of extended edge and localized bulk energy levels in macroscopic Hall systems

We study the spectrum of a random Schroedinger operator for an electron submitted to a magnetic field in a finite but macroscopic two dimensional system of linear dimensions equal to L. The y direction is periodic and in the x direction the electron is confined by two smooth increasing boundary potentials. The eigenvalues of the Hamiltonian are classified according to their associated quantum mechanical current in the y direction. Here we look at an interval of energies inside the first Landau band of the random operator for the infinite plane. In this energy interval, with large probability, there exist O(L) eigenvalues with positive or negative currents of O(1). Between each of these there exist O(L^2) eigenvalues with infinitesimal current O(exp(-cB(log L)^2)). We explain what is the relevance of this analysis to the integer quantum Hall effect.Comment: 29 pages, no figure

Exportaciones y Productividad: ¿El destino importa?

In this work, we analyze the effect of export destinations on Total Factor Productivity (TFP) of manufacturing Uruguayan firms for the period 1997-2006. We study two effects: self-selection and learning by exporting. There is evidence of self-selection with a stronger effect for firms exporting to developed countries. Nevertheless, applying transition groups methodology in order to mitigate endogeneity issues, there is no evidence that exporting to developed countries enhances productivity through learning by exporting. However, evidence of learning by exporting is found for those firms starting to export to less developed countries. These findings suggest an international strategy through which firms reach gains in productivity exporting to markets with lower entry cost, and once they have learned and improved their productivity, are in a better position to enter more developed countries.En este trabajo se analiza el efecto del destino de las exportaciones sobre la productividad total de los factores de las empresas manufactureras uruguayas, para el periodo 1997-2006. Se estudian dos efectos: autoselección y aprendizaje a través de las exportaciones. Se encuentra evidencia de autoselección con un efecto mayor para las empresas que exportan a los países desarrollados. Sin embargo, aplicando la metodología de grupos de transición, a efectos de mitigar los problemas de endogeneidad, no hay evidencia de que las exportaciones a países desarrollados aumente la productividad a través del aprendizaje por exportar. Sin embargo, si hay evidencia de aprendizaje por exportar para aquellas empresas que empiezan a exportar a países de la región, menos desarrollados. Estos hallazgos sugieren una estrategia internacional en la cual las firmas logran ganancias de productividad exportando a mercados con menores costos de entrada, y una vez que han adquirido experiencia-aprendido- y aumentado su productividad, están en una mejor posición para entrar en los mercados de los países desarrollados

Individual Responses to Business Tendency Surveys and the Forecasting of Manufacturing Production

We compare the performances of balances of opinion to those of indicators introduced by Mitchell, Smith and Weale for the one-quarter forecasting of the manufacturing production growth rate. These indicators take into account the heterogeneity of the response behaviours of the entrepreneurs taking part in the Business Tendency Survey. The responses which are the most tightly linked to the overall fluctuations of manufactured production contribute to the variability of these indicators to a larger extent than the responses of the other surveyed. The application of Mitchell, Smith and Weale to British and German data seems to suggest that these indicators perform better in short-term forecasting than the balances of opinion, but their application to Swedish and Portuguese data suggests not. In our study carried out using French data, their predictive performances turn out to be inferior or, at best, equivalent to those of the balances of opinion.Business Tendency Surveys, Quantification, Dis-Aggregate Indicators, Short-Term Forecasting

The Impact of Finite-Amplitude Bottom Topography on Internal Wave Generation in the Southern Ocean

Direct observations in the Southern Ocean report enhanced internal wave activity and turbulence in a kilometer-thick layer above rough bottom topography collocated with the deep-reaching fronts of the Antarctic Circumpolar Current. Linear theory, corrected for finite-amplitude topography based on idealized, two-dimensional numerical simulations, has been recently used to estimate the global distribution of internal wave generation by oceanic currents and eddies. The global estimate shows that the topographic wave generation is a significant sink of energy for geostrophic flows and a source of energy for turbulent mixing in the deep ocean. However, comparison with recent observations from the Diapycnal and Isopycnal Mixing Experiment in the Southern Ocean shows that the linear theory predictions and idealized two-dimensional simulations grossly overestimate the observed levels of turbulent energy dissipation. This study presents two- and three-dimensional, realistic topography simulations of internal lee-wave generation from a steady flow interacting with topography with parameters typical of Drake Passage. The results demonstrate that internal wave generation at three-dimensional, finite bottom topography is reduced compared to the two-dimensional case. The reduction is primarily associated with finite-amplitude bottom topography effects that suppress vertical motions and thus reduce the amplitude of the internal waves radiated from topography. The implication of these results for the global lee-wave generation is discussed.National Science Foundation (U.S.) (Award CMG-1024198

Gibbs measures over permutations of point processes with low density

We study a model of spatial random permutations over a discrete set of points. Formally, a permutation σ is sampled proportionally to the weight exp{−α∑_xV(σ(x)−x)}, where α>0 is the temperature and V is a non-negative and continuous potential. The most relevant case for physics is when V(x)=‖x‖^2, since it is related to Bose-Einstein condensation through a representation introduced by Feynman in 1953. In the context of statistical mechanics, the weights (1) define a probability when the set of points is finite, but the construction associated to an infinite set is not trivial and may fail without appropriate hypotheses. The first problem is to establish conditions for the existence of such a measure at infinite volume when the set of points is infinite. Once existence is derived, we are interested in establishing its uniqueness and the cycle structure of a typical permutation. We here consider the large temperature regime when the set of points is a Poisson point process in ℤ^d with intensity ρ∈(0,1/2), and the potential verifies some regularity conditions. In particular, we prove that if α is large enough, for almost every realization of the point process, there exists a unique Gibbs measure that concentrates on finite cycle permutations. We then extend these results to the continuous setting, when the set of points is given by a Poisson point process in ℝ^d with low enough intensity.Fil: Armendáriz, María Inés. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Investigaciones Matemáticas "Luis A. Santaló". Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Matemáticas "Luis A. Santaló"; ArgentinaFil: Ferrari, Pablo Augusto. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Investigaciones Matemáticas "Luis A. Santaló". Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Matemáticas "Luis A. Santaló"; ArgentinaFil: Frevenza Maestrone, Nicolas Federico. Universidad de Buenos Aires; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin