Classification methods for Hilbert data based on surrogate density

An unsupervised and a supervised classification approaches for Hilbert random curves are studied. Both rest on the use of a surrogate of the probability density which is defined, in a distribution-free mixture context, from an asymptotic factorization of the small-ball probability. That surrogate density is estimated by a kernel approach from the principal components of the data. The focus is on the illustration of the classification algorithms and the computational implications, with particular attention to the tuning of the parameters involved. Some asymptotic results are sketched. Applications on simulated and real datasets show how the proposed methods work.Comment: 33 pages, 11 figures, 6 table

Leviathan as a Minority Shareholder: A Study of Equity Purchases by the Brazilian National Development Bank (BNDES), 1995-2003

There is a growing literature comparing the performance of private vs. state-owned companies. Yet, there is little work examining the effects of having the government as a minority shareholder of private companies. We conduct such a study using data for 296 publicly-traded corporations in Brazil, looking at the effects of equity purchases by the National Bank for Economic and Social Development (BNDES) on firm performance between 1995 and 2003. Our fixed-effects regressions show that BNDES's purchases of equity lead to increases in return on assets and investment in fixed assets. Finally, we find that the positive effect of BNDES' equity purchases is reduced when the target firms belong to state-owned and private pyramidal groups. Therefore, our argue that having development banks owning minority stakes can have a positive effect on performance as long as they promote long-term investments and are shielded from governmental interference and potential minority shareholder expropriation.

How to detect an anti-spacetime

Is it possible, in principle, to measure the sign of the Lapse? We show that fermion dynamics distinguishes spacetimes having the same metric but different tetrads, for instance a Lapse with opposite sign. This sign might be a physical quantity not captured by the metric. We discuss its possible role in quantum gravity.Comment: Article awarded with an "Honorable Mention" from the 2012 Gravity Foundation Award. 6 pages, 8 (pretty) figure

Polymorphism, phonon dynamics and carrier-phonon coupling in pentacene

The crystal structure and phonon dynamics of pentacene is computed with the Quasi Harmonic Lattice Dynamics (QHLD) method, based on atom-atom potential. We show that two crystalline phases of pentacene exist, rather similar in thermodynamic stability and in molecular density. The two phases can be easily distinguished by Raman spectroscopy in the 10-100 cm-1 spectral region. We have not found any temperature induced phase transition, whereas a sluggish phase change to the denser phase is induced by pressure. The bandwidths of the two phases are slightly different. The charge carrier coupling to low-frequency phonons is calculated.Comment: 6 pages, 3 figures. Presented at ICFPAM-

Leviathan in Business: Varieties of State Capitalism and their Implications for Economic Performance

In this paper we document the extent and reach of state capitalism around the world and explore its economic implications. We focus on governmental provision of capital to corporations – either equity or debt – as a defining feature of state capitalism. We present a stylized distinction between two broad, general varieties of state capitalism: one through majority control of publicly traded companies (e.g. state-controlled SOEs) and a hybrid form that relies on minority investments in companies by development banks, pension funds, sovereign wealth funds, and the government itself. We label these two alternative modes Leviathan as a majority investor and Leviathan as a minority investor, respectively. Next we differentiate between these two modes by describing their key fundamental traits and the conditions that should make each mode more conducive to development and superior economic performance