Abelian fibrations and SYZ mirror conjecture

SYZ mirror conjecture predicts that a Calabi-Yau manifold $X$ consists of a family of tori which are dual to a family of special lagrangian tori on the mirror dual manifold $\hat{X}$. Here we consider a fibration of polarized abelian varieties and we construct a dual one. Moreover we prove that they are equivalent at the level of derived categories.Comment: C. R. Acad. Sci. Paris. Ser. I (2012), to appea

Ownership structure and risk at Colombian banks

The separation between ownership and the control of capital in banks generates differences in thepreferences for risk among shareholders and the manager. These differences could imply a corporate governance problem in banks with a dispersed ownership, since owners fail to exert control in the allocation of capital. In this paper we examine the relationship between the ownership structure and risk for Colombian banks. Our results suggest that a high ownership concentration leads to higher levels of risk.corporate governance and banking risk

Examining the Impact of Innovation Forms on Sustainable Economic Performance: The Influence of Family Management

The aim of this research is to explore the effect that innovation, as a potential source of sustained competitive advantage and firm growth, has on the achievement of sustainable economic performance. In particular, this paper empirically examines the influence of four innovation forms (intramural R&D, extramural R&D, product innovation, and process innovation) on firms’ sustainable economic performance, considering the moderating effect of family involvement in management. To test the hypotheses, random-effects regression analyses are applied to a longitudinal sample of 598 Spanish private manufacturing firms throughout the 2006–2015 period. The results show a negative effect of intramural and extramural R&D on sustainable economic performance and a positive effect of process innovation on sustainable economic performance. Moreover, a reinforced relationship between process innovation and sustainable economic performance is also revealed when family involvement in management acts as a moderator. The findings make several contributions to research and practice

On the Utility of the Inverse Gamma Distribution in Modeling Composite Fading Channels

We introduce a general approach to characterize composite fading models based on inverse gamma (IG) shadowing. We first determine to what extent the IG distribution is an adequate choice for modeling shadow fading, by means of a comprehensive test with field measurements and other distributions conventionally used for this purpose. Then, we prove that the probability density function and cumulative density function of any IG-based composite fading model are directly expressed in terms of a Laplace-domain statistic of the underlying fast fading model, and in some relevant cases, as a mixture of well-known state-of-the-art distributions. We exemplify our approach by presenting a composite IG/two-wave with diffuse power fading model, for which its statistical characterization is directly attained in a simple form.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Changes in hydrodynamic, structural and geochemical properties in carbonate rock samples due to reactive transport

Reactive transport plays an important role in the development of a wide range of both anthropic and natural processes affecting geological media. To predict the consequences of reactive transport processes on structural and hydrodynamic properties of a porous media at large time and spatial scales, numerical modeling is a powerful tool. Nevertheless, such models, to be realistic, need geochemical, structural and hydrodynamic data inputs representative of the studied reservoir or material. Here, we present an experimental study coupling traditional laboratory measurements and percolation experiments in order to obtain the parameters that define rock heterogeneity, which can be altered during the percolation of a reactive fluid. In order to validate the experimental methodology and identify the role of the initial heterogeneities on the localization of the reactive transport processes, we used three different limestones with different petrophysical characteristics. We tracked the changes of geochemical, structural and hydrodynamic parameters in these samples induced by the percolation of an acid fluid by measuring, before and after the percolation experiment, petrophysical and hydrodynamic properties of the rocks.Peer ReviewedPostprint (published version