276 research outputs found
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 dinĂĄmica de este fluido hace posible el funcionamiento de los ecosistemas terrestres y acuĂĄticos continentales tal como los conocemos. Factores locales como las precipitaciones atmosfĂ©ricas (secas y hĂșmedas) o la calidad de la radiaciĂłn solar que llega al suelo, muy afectada por el contenido de aerosoles en la troposfera, dependen de fenĂłmenos que pueden ocurrir a miles de kilĂłmetros. Los ecosistemas de alta montaña, como la Sierra Nevada del sur ibĂ©rico, son los sensores mĂĄs 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
- âŠ