Classical trajectories in quantum transport at the band center of bipartite lattices with or without vacancies

Here we report on several anomalies in quantum transport at the band center of a bipartite lattice with vacancies that are surely due to its chiral symmetry, namely: no weak localization effect shows up, and, when leads have a single channel the transmission is either one or zero. We propose that these are a consequence of both the chiral symmetry and the large number of states at the band center. The probability amplitude associated to the eigenstate that gives unit transmission ressembles a classical trajectory both with or without vacancies. The large number of states allows to build up trajectories that elude the blocking vacancies explaining the absence of weak localization.Comment: 5 pages, 5 figure

Beyond the work-life balance: family and international mobility of the highly skilled

International mobility of the highly skilled has become one of the cornerstones of development in the current knowledge society. Correspondingly, highly skilled personnel are impelled to move abroad in order to improve their competences and build influential professional networks. Mobility implies some advantages involving personal, social and family opportunities when movers experience handicaps in their country of origin. For movers, mobility becomes a new challenge beyond the work-family balance, particularly for women who usually take on the lion's share of childcare and domestic tasks within the family. The literature exploring the gender dimension in relation to international mobility points to complex outcomes. Firstly, women are taking on a more active role in international mobility processes, even when they have family. Secondly, family and international mobility are interrelated both for men and for women, although family could become a hindrance, particularly for women. Thirdly, international mobility and women's career development may interfere with family formation or modify traditional family values. Finally, families moving abroad constitute a challenge for public policy, since they present a new area of problems. We aim to analyse the relationship between international mobility and family based on in-depth interviews from a purposive sample of highly skilled personnel in science and technology. The results of our research suggest that international mobility of the highly skilled has effects on the family and vice versa; however, while international mobility and family are compatible, measures and policies to reconcile them are still insufficient

International mobility of women in science and technology careers: shaping plans for personal and professional purposes

International mobility has become a key requirement in science and technology (S&T) professional career progression. On the one hand, the increasing mobility of women suggests that this may be a way for them to avoid or get away from women-unfriendly working environments. On the other hand, international mobility can present problems for women as they, particularly, have to plan their lives around their professional goals and personal lives. This article addresses the international mobility strategies of women regarding their personal and professional choices. We analyse their motivations to move, the way they manage their lives abroad and the effects of mobility on their lives. The analysis is based on 24 in-depth interviews of highly skilled women working in Spanish S&T sectors. Our main findings show that mobility is a new challenge which may improve women's family lives and professional careers. However, they have to plan carefully their lives on a long-term as well as a daily basis. In this sense, they need strong personal determination and the ability to balance their professional and personal goals. Moreover, their personal decisions depend not only on them as individuals, but also on their partners and families, on wider social values, on the institutional support they enjoy, and on the general public policies which they are affected by

Hyperparameter optimization using agents for large scale machine learning

Machine learning (ML) has become an essential tool for humans to get rational predictions in different aspects of their lives. Hyperparameter algorithms are a tool for creating better ML models. The hyperparameter algorithms are an iterative execution of trial sets. Usually, the trials tend to have a different execution time. In this paper we are optimizing the grid and random search with cross-validation from the Dislib [1] an ML library for distributed computing built on top of PyCOMPSs[2] programming model, inspired by the Maggy [3], an open-source framework based on Spark. This optimization will use agents and avoid the trials to wait for each other, achieving a speed-up of over x2.5 compared to the previous implementation

Estratigrafía del Paleógeno en la zona de tránsito entre la Codillera prelitoral Catalana y el Prepirineo

El estudio de la serie eocénica de El Far-Puig del Moro (Gerona) y la subsiguiente comparación con el Eoceno de Vic (Barcelona), permite situar la estratigrafía del Eoceno inferior y medio en la zona de tránsito entre la Cordillera Prelitoral y el Prepirineo. A través de unidades litostratigráficas detalladamente descritas, así como de las atribuciones cronostratigráficas,se tiene una visión útil para las investigaciones posteriores ya iniciadas sobre el Eoceno pirenaico y subpirenaico