Quantum entanglement in the neighborhood of pseudo-transition for a spin-1/2 Ising-XYZ diamond chain

Recently has been observed for some one-dimensional models that exhibit unexpected pseudo-transitions and quasi-phases. This pseudo-transition resembles a first- and second-order phase transition simultaneously. One of those models is the spin-1/2 Ising-XYZ diamond chain, composed of Ising spin particles at the nodal sites and the Heisenberg spin particles at the interstitial sites. Where we assume Ising-type interaction between the nodal and interstitial sites, the Heisenberg-type interaction between interstitial sites, and with an external magnetic field applied along the z-axis. This model presents an exact analytical solution applying the transfer matrix technique, which shows 3 phases at zero temperature in the vicinity of pseudo-transition. The pseudo-transition separates quasi-phases, these quasi-phases still hold at a finite temperature most of the pattern configurations of a true phase at zero temperature. Here we study the quantum entanglement of pair spin particles in the quasi-phase regions, which can be measured through the concurrence. Then we observe an unexpected behavior in the concurrence, that is below pseudo-critical temperature the concurrence remains almost constant up to pseudo-critical temperature, but above the pseudo-critical temperature, the concurrence behaves as for the standard one-dimensional spin models. Further, we consider the entropy behavior of the system, below pseudo-critical temperature the entropy becomes almost null, while above pseudo-critical temperature the system exhibits standard behavior as for ordinary one-dimensional spin models.Comment: 5 pages, 2 figure

Mergers and Acquisitions in the Colombian Financial Sector (Impact on Efficiency 1990-2005)

Colombia has witnessed a renewed interest in merging and acquiring financial institutions during 2003-2005. These have been “complementary mergers” that seek to exploit economies scale and scope. This process contrasts favorably with those mergers & acquisitions that occurred during the mid-1990s, which involved mainly “twin institutions” that lacked potential for gaining multiproduct efficiency. This document analyzes the need to remove some of the regulatory constraints that obstruct further exploitation of such economies of scale-scope and quantifies the “cost efficiencies” shown by the Colombian banking sector (1994-2005). At the aggregate level, we found (absolute) banking efficiency to be around 63%, a similar value to those found in related studies post-crisis. This implies that banks operating in Colombia have been able to recover their efficiency levels during postcrisis 2003-2005, except for mortgage institutions. We highlight regulatory barriers that could be removed to help the banking system move closer to the optimal production frontier.Financial Institutions, Mergers and Acquisitions

Semiparametric Cross Entropy for rare-event simulation

The Cross Entropy method is a well-known adaptive importance sampling method for rare-event probability estimation, which requires estimating an optimal importance sampling density within a parametric class. In this article we estimate an optimal importance sampling density within a wider semiparametric class of distributions. We show that this semiparametric version of the Cross Entropy method frequently yields efficient estimators. We illustrate the excellent practical performance of the method with numerical experiments and show that for the problems we consider it typically outperforms alternative schemes by orders of magnitude

Family Income Inequality and the Role of Wives Earnings in Mexico: 1988-2010

We study family income inequality in Mexico from 1988 to 2010. Female labor supply increased during this period, especially for married women. The share of wives’ income among married couples grew from 13 percent in 1988 to 23 percent in 2010. However, the correlation of husbands’ and wives’ earnings has been fairly stable with a value close to 0.28, one of the highest correlations recorded across countries. We follow Cancian and Reed’s (1999) methodology in order to analyze whether wives’ income equalizes total family income distribution. We investigate several counterfactuals and conclude that the recent increment in female employment has contributed to a decrease in family income inequality mainly through a rise in wives’ labor supply in poor families.income inequality, female employment, female earnings, Latin America, Mexico

2D-Drop model applied to the calculation of step formation energies on a (111) substrate

A model is presented for obtaining the step formation energy for metallic islands on (111) surfaces from Monte Carlo simulations. This model is applied to homo (Cu/Cu(111), Ag/Ag(111)) and heteroepitaxy (Ag/Pt(111)) systems. The embedded atom method is used to represent the interaction between the particles of the system, but any other type of potential could be used as well. The formulation can also be employed to consider the case of other single crystal surfaces, since the higher barriers for atom motion on other surfaces are not a hindrance for the simulation scheme proposed.Comment: 12 pages, LaTeX2e, 2 included EPS figures, submitted to Surface Science Subj-clas

Carbonation of concrete with construction and demolition waste based recycled aggregates and cement with recycled content

Durability is a major concern in concrete (particularly recycled concrete) structures exposed to carbonation-induced corrosion, given the social, economic, environmental and safety implications involved. This article explores carbonation performance in concrete with 25% or 50% mixed recycled construction and demolition waste aggregate, alone or in conjunction with cement containing 25% fired clay construction and demolition waste. Irrespective of cement type, the mean carbonation depth was slightly greater in materials with 25% or 50% recycled aggregate than in concretes with 100% natural aggregate, although the difference was not statistically significant for the 25% replacement ratio. In all the concretes studied, the carbonation coefficient was below the 4 mm/yr0.5 indicative of good quality. Based on the prediction model proposed in Spain’s concrete code, reinforcement passivity was guaranteed in all these types of concrete when exposed to class XC1 to XC4 carbonation environments for substantially longer than their 100 year design service life.This study was funded under research projects BIA 2013-48876-C3-1-R, BIA2013-48876-C3-2-R and BIA2016-76643-C3-1-R awarded by the Ministry of Science and Innovation and grant GR 18122 awarded to the MATERIA Research Group by the Regional Government of Extremadura and the European Regional Development Fund, ERDF. In 2016 University of Extremadura teaching and research personnel benefitted from a mobility grant (MOV15A029) awarded by the Regional Government of Extremadura and in 2018 from a José Castillejo (CAS17/00313) scholarship granted by the Spanish Ministry of Education, Culture and Sport. Philip Van den Heede is since October 2017 a postdoctoral fellow of the Research Foundation—Flanders (FWO) (project number 3E013917) and acknowledges its support.Peer reviewe

The Signature Triality of Majorana-Weyl Spacetimes

Higher dimensional Majorana-Weyl spacetimes present space-time dualities which are induced by the Spin(8) triality automorphisms. Different signature versions of theories such as 10-dimensional SYM's, superstrings, five-branes, F-theory, are shown to be interconnected via the S_3 permutation group. Bilinear and trilinear invariants under space-time triality are introduced and their possible relevance in building models possessing a space-versus-time exchange symmetry is discussed. Moreover the Cartan's ``vector/chiral spinor/antichiral spinor" triality of SO(8) and SO(4,4) is analyzed in detail and explicit formulas are produced in a Majorana-Weyl basis. This paper is the extended version of hep-th/9907148.Comment: 28 pages, LaTex. Extended version of hep-th/990714

High resolution spectroscopic analysis of seven giants in the bulge globular cluster NGC 6723

Globular clusters associated with the Galactic bulge are important tracers of stellar populations in the inner Galaxy. High resolution analysis of stars in these clusters allows us to characterize them in terms of kinematics, metallicity, and individual abundances, and to compare these fingerprints with those characterizing field populations. We present iron and element ratios for seven red giant stars in the globular cluster NGC~6723, based on high resolution spectroscopy. High resolution spectra ($R\sim48~000$) of seven K giants belonging to NGC 6723 were obtained with the FEROS spectrograph at the MPG/ESO 2.2m telescope. Photospheric parameters were derived from $\sim130$ FeI and FeII transitions. Abundance ratios were obtained from line-to-line spectrum synthesis calculations on clean selected features. An intermediate metallicity of [Fe/H]$=-0.98\pm0.08$ dex and a heliocentric radial velocity of $v_{hel}=-96.6\pm1.3~km s^{-1}$ were found for NGC 6723. Alpha-element abundances present enhancements of $[O/Fe]=0.29\pm0.18$ dex, $[Mg/Fe]=0.23\pm0.10$ dex, $[Si/Fe]=0.36\pm0.05$ dex, and $[Ca/Fe]=0.30\pm0.07$ dex. Similar overabundance is found for the iron-peak Ti with $[Ti/Fe]=0.24\pm0.09$ dex. Odd-Z elements Na and Al present abundances of $[Na/Fe]=0.00\pm0.21$ dex and $[Al/Fe]=0.31\pm0.21$ dex, respectively. Finally, the s-element Ba is also enhanced by $[Ba/Fe]=0.22\pm0.21$ dex. The enhancement levels of NGC 6723 are comparable to those of other metal-intermediate bulge globular clusters. In turn, these enhancement levels are compatible with the abundance profiles displayed by bulge field stars at that metallicity. This hints at a possible similar chemical evolution with globular clusters and the metal-poor of the bulge going through an early prompt chemical enrichment

High-resolution magnetic penetration depth and inhomogeneities in locally noncentrosymmetric SrPtAs

We present a magnetic-penetration-depth study on polycrystalline and granular samples of SrPtAs, a pnictide superconductor with a hexagonal structure containing PtAs layers that individually break inversion symmetry (local noncentrosymmetry). Compact samples show a clear-cut s-wave-type BCS behavior, which we consider to be the intrinsic penetration depth of SrPtAs. Granular samples display a sample-dependent second diamagnetic drop, attributed to the intergrain coupling. Our experimental results point to a nodeless isotropic superconducting energy gap in SrPtAs, which puts strong constraints on the driven mechanism for superconductivity and the order parameter symmetry of this compound