Comparing TFP Catching-up and Capital Deepening in US and European Growths: A Directional Distance Function Approach

In Solow’s model the income convergence between countries arises from two main sources: a capital deepening effect resulting from the diminishing returns of the production technology and a technological transfer/diffusion effect related to Total Factor Productivity (TFP) differences. A large literature has been devoted to analyze these effects but most of the studies suffer from three weaknesses by defining the US as the a priori technological leader, by using a parametric functional form and by assuming constant returns to scale for the technology. Our paper offers an alternative approach based on a non-parametric programming framework and the estimation of directional distance functions. We explicitly separate country TFP differences into two components: a technology effect and a scale effect to study the catching-up process on each of them. We also analyze the role of the capital deepening effect by introducing a relevant measure of the structural efficiency which reveals inefficiencies due to changes in input-ratio differences. Our empirical work focuses on 15 European countries (EU) and the US over the period 1980-2004. We use time series procedures to test for convergence for individual countries or sub-sets of countries.TFP Catching-up, Capital Deepening, Convergence, Directional Distance Function. Running title: Comparing TFP Catching-up and Capital Deepening

Polynomial-Time Key Recovery Attack on the Faure-Loidreau Scheme based on Gabidulin Codes

Encryption schemes based on the rank metric lead to small public key sizes of order of few thousands bytes which represents a very attractive feature compared to Hamming metric-based encryption schemes where public key sizes are of order of hundreds of thousands bytes even with additional structures like the cyclicity. The main tool for building public key encryption schemes in rank metric is the McEliece encryption setting used with the family of Gabidulin codes. Since the original scheme proposed in 1991 by Gabidulin, Paramonov and Tretjakov, many systems have been proposed based on different masking techniques for Gabidulin codes. Nevertheless, over the years all these systems were attacked essentially by the use of an attack proposed by Overbeck. In 2005 Faure and Loidreau designed a rank-metric encryption scheme which was not in the McEliece setting. The scheme is very efficient, with small public keys of size a few kiloBytes and with security closely related to the linearized polynomial reconstruction problem which corresponds to the decoding problem of Gabidulin codes. The structure of the scheme differs considerably from the classical McEliece setting and until our work, the scheme had never been attacked. We show in this article that this scheme like other schemes based on Gabidulin codes, is also vulnerable to a polynomial-time attack that recovers the private key by applying Overbeck's attack on an appropriate public code. As an example we break concrete proposed $80$ bits security parameters in a few seconds.Comment: To appear in Designs, Codes and Cryptography Journa

Could Society’s willingness to reduce pesticide use be aligned with Farmers’ economic self-interest?

agricultural intensification (AI), agricultural extensification (AE), pesticide reduction, environmental performance, non parametric cost-functions

Linear programming solutions and distance functions under a constant returns to scale technology

This note generalizes analytical relationships among activity variables of DEA models previously derived by Boussemart, Briec and Leleu (2007). We relax the asumption of constant returns to scale by showing that the key results hold under a weaker asumption of homogeneity. We use the notion of alpha-returns to scale to extend the analysis to strictly increasing and decreasing returns, covering now the whole range of returns to scale for multi-output homogenous technologies.Data envelopment analysis, Methodology, Production

Molecular phylogeny: pitfalls and progress

Molecular phylogeny based on nucleotide or amino acid sequence comparison has become a widespread tool for general taxonomy and evolutionary analyses. It seems the only means to establish a natural classification of microorganisms, since their phenotypic traits are not always consistent with genealogy. After an optimistic period during which comprehensive microbial evolutionary pictures appeared, the discovery of several pitfalls affecting molecular phylogenetic reconstruction challenged the general validity of this approach. In addition to biological factors, such as horizontal gene transfer, some methodological problems may produce misleading phylogenies. They are essentially (i) loss of phylogenetic signal by the accumulation of overlapping mutations, (ii) incongruity between the real evolutionary process and the assumed models of sequence evolution, and (iii) differences of evolutionary rates among species or among positions within a sequence. Here, we discuss these problems and some strategies proposed to overcome their effects