Enhancement of entanglement in one-dimensional disordered systems

The pairwise quantum entanglement of sites in disordered electronic one-dimensional systems (rings) is studied. We focus on the effect of diagonal and off diagonal disorder on the concurrence $C_{ij}$ between electrons on neighbor and non neighbor sites $i,j$ as a function of band filling. In the case of diagonal disorder, increasing the degree of disorder leads to a decrease of the concurrence with respect to the ordered case. However, off-diagonal disorder produces a surprisingly strong enhancement of entanglement. This remarkable effect occurs near half filling, where the concurrence becomes up to 15% larger than in the ordered system.Comment: 21 pages, 9 figure

MOCCA-SURVEY database I. Accreting white dwarf binary systems in globular clusters -- IV. cataclysmic variables -- properties of bright and faint populations

We investigate here populations of cataclysmic variables (CVs) in a set of 288 globular cluster (GC) models evolved with the MOCCA code. This is by far the largest sample of GC models ever analysed with respect to CVs. Contrary to what has been argued for a long time, we found that dynamical destruction of primordial CV progenitors is much stronger in GCs than dynamical formation of CVs, and that dynamically formed CVs and CVs formed under no/weak influence of dynamics have similar white dwarf mass distributions. In addition, we found that, on average, the detectable CV population is predominantly composed of CVs formed via typical common envelope phase (CEP) ($\gtrsim70$ per cent), that only $\approx2-4$ per cent of all CVs in a GC is likely to be detectable, and that core-collapsed models tend to have higher fractions of bright CVs than non-core-collapsed ones. We also consistently show, for the first time, that the properties of bright and faint CVs can be understood by means of the pre-CV and CV formation rates, their properties at their formation times and cluster half-mass relaxation times. Finally, we show that models following the initial binary population proposed by Kroupa and set with low CEP efficiency better reproduce the observed amount of CVs and CV candidates in NGC 6397, NGC 6752 and 47 Tuc. To progress with comparisons, the essential next step is to properly characterize the candidates as CVs (e.g. by obtaining orbital periods and mass ratios).Comment: 18 pages, 13 figures; accepted for publication in MNRA

Balance hídrico para riego en la microcuenca del río Blanco Cayambe – Ecuador 2009

La microcuenca del río Blanco, contempla las comunidades Ancholag Alto, Ancholag Bajo, Santa Anita de Ancholag, Santo Domingo Núm. 1 y los barrios Puntiachil, Santo Domingo de Guzmán, Nápoles, Miraflores, Granobles, Sigzal Bajo y la zona urbana de Cayambe y Ayora y abarca una superficie de 4.799 ha, con una superficie potencialmente regable de 1.927 ha. El objetivo del estudio fue analizar el estado actual del recurso hídrico considerando su distribución espacial y temporal de oferta y demanda, permitiendo desarrollar un adecuado uso según las dinámicas productivas de sus diferentes usuarios

Covariant Impulse Approximation for the study of the internal structure of composite particles

We present a brief review on the Impulse Approximation method to study processes of scattering off composite particles. We first construct the model in a non-relativistic fashion that enables us to extend the model to a covariant Impulse Approximation, which is needed for the study of high momentum transfer processes.Comment: 8 Page

Collective Social Capital Within a Performance-Based Management System

Local education agencies utilizing performance-based management systems as a means to improve educator effectiveness and student performance is becoming more prevalent within the United States. High-need schools are implementing these systems and endeavor to create an environment that promotes a professional learning community that improves educator quality and student achievement. This study seeks to measure the level of collective social capital generated by the implementation of one such management system, Rewarding Excellence in Instruction and Leadership, through the use of a sociological case study. Through the use of document analysis and interviews, the degree of collective social capital fostered will be sought to better understand the potential for impacting educator effectiveness