Bifurcations in synergistic epidemics on random regular graphs

The role of cooperative effects (i.e. synergy) in transmission of infection is investigated analytically and numerically for epidemics following the rules of susceptible-infected-susceptible (SIS) model defined on random regular graphs. Non-linear dynamics are shown to lead to bifurcation diagrams for such spreading phenomena exhibiting three distinct regimes: non-active, active and bi-stable. The dependence of bifurcation loci on node degree is studied and interesting effects are found that contrast with the behaviour expected for non-synergistic epidemics.FJPR acknowledges financial support from the Carnegie Trust

Excellence and Quality in Andalusia University Library System

From 1996 onwards, then, the Quality Assessment National Plan and the adoption of its agenda by regional authorities and Universities alike has resulted in a growing acceptance by the Spanish academic community of the challenges and opportunities offered by evaluation and quality assurance activities. Academic librarians have been committed to this culture of quality from the very beginnings and in most cases have being leading the way in their own institutions. General tools like the Evaluation Guide referred to above developed to be applied in administration and services alike were of little use for libraries, so academic libraries have been the first units to develop their own evaluation guides at local and regional levels. University System in Andalusia (Spain) is formed by 10 Universities financed by regional government. The Quality Unit of Andalusia Universities convened in 2000 an Assessment University Libraries Pilot Plan to do a global analysis of the Library System. This Pilot Plan has had three steps: - During 2000-2002, a technical committee to draft a new evaluation guide for academic libraries. Based on the EFQM, because of its growing influence in the evaluation of the public sector and not-for-profit organizations across Europe. During the course of our work we were delighted to see that we concurred basically with the approach taken by LISIM. The Guide is divided into 5 parts, as follows: Analysis and Description of 9 criteria adapted to library scenario, 35 Tables for data collection, a set of 30 quality and performance Indicators, a Excellence-rating matrix, an objective tool, to determine the level of excellence achieved by the library on a scale from 0 to 10, and General guidelines for the Assessment Committees of University Departments (the basic unit of research assessment undertaken by the University) and of degree courses (the basic unit of assessment of teaching personnel). - In 2002-2004, a coordination committee drove the assessment process of 9 libraries and tested materials and evaluation methodology. The Pilot Plan has finalised with External Evaluation for 5 External Committee formed by librarians, faculties and EFQM methodology specialist. The aim of this paper is explain different parts and strong points of this process and how EFQM is suitable for all kind of librarie

Modelling avalanches in martensites

Solids subject to continuous changes of temperature or mechanical load often exhibit discontinuous avalanche-like responses. For instance, avalanche dynamics have been observed during plastic deformation, fracture, domain switching in ferroic materials or martensitic transformations. The statistical analysis of avalanches reveals a very complex scenario with a distinctive lack of characteristic scales. Much effort has been devoted in the last decades to understand the origin and ubiquity of scale-free behaviour in solids and many other systems. This chapter reviews some efforts to understand the characteristics of avalanches in martensites through mathematical modelling.Comment: Chapter in the book "Avalanches in Functional Materials and Geophysics", edited by E. K. H. Salje, A. Saxena, and A. Planes. The final publication is available at Springer via http://dx.doi.org/10.1007/978-3-319-45612-6_

Ecosistemas de alta montaña, las atalayas de la troposfera

La troposfera es el fluido en el que vivimos los organismos terrestres. La dinámica de este fluido hace posible el funcionamiento de los ecosistemas terrestres y acuáticos continentales tal como los conocemos. Factores locales como las precipitaciones atmosféricas (secas y húmedas) o la calidad de la radiación solar que llega al suelo, muy afectada por el contenido de aerosoles en la troposfera, dependen de fenómenos que pueden ocurrir a miles de kilómetros. Los ecosistemas de alta montaña, como la Sierra Nevada del sur ibérico, son los sensores más finos que poseemos para el estudio de los efectos de esos factores y para detectar pronto sus tendencias y cambios

Driving rate effects in avalanche-mediated, first-order phase transitions

We have studied the driving rate and temperature dependence of the power-law exponents that characterize the avalanche distribution in first-order phase transitions. Measurements of acoustic emission in structural transitions in Cu-Zn-Al and Cu-Al-Ni are presented. We show how the observed behaviour emerges within a general framework of competing time scales of avalanche relaxation, driving rate, and thermal fluctuations. We have confirmed our findings by numerical simulations of a prototype model.Comment: 4 pages, 3 figure

Training-induced criticality in martensites

We propose an explanation for the self-organization towards criticality observed in martensites during the cyclic process known as `training'. The scale-free behavior originates from the interplay between the reversible phase transformation and the concurrent activity of lattice defects. The basis of the model is a continuous dynamical system on a rugged energy landscape, which in the quasi-static limit reduces to a sandpile automaton. We reproduce all the principal observations in thermally driven martensites, including power-law statistics, hysteresis shakedown, asymmetric signal shapes, and correlated disorder.Comment: 5 pages, 4 figure

Stable, metastable and unstable states in the mean-field RFIM at T=0

We compute the probability of finding metastable states at a given field in the mean-field random field Ising model at T=0. Remarkably, this probability is finite in the thermodynamic limit, even on the so-called ``unstable'' branch of the magnetization curve. This implies that the branch is reachable when the magnetization is controlled instead of the magnetic field, in contrast with the situation in the pure system.Comment: 10 pages, 3 figure

Capillary condensation in one-dimensional irregular confinement

Peer reviewedPublisher PD