First-order phase transition in a 2D random-field Ising model with conflicting dynamics

The effects of locally random magnetic fields are considered in a nonequilibrium Ising model defined on a square lattice with nearest-neighbors interactions. In order to generate the random magnetic fields, we have considered random variables $\{h\}$ that change randomly with time according to a double-gaussian probability distribution, which consists of two single gaussian distributions, centered at $+h_{o}$ and $-h_{o}$, with the same width $\sigma$. This distribution is very general, and can recover in appropriate limits the bimodal distribution ($\sigma\to 0$) and the single gaussian one ($ho=0$). We performed Monte Carlo simulations in lattices with linear sizes in the range $L=32 - 512$. The system exhibits ferromagnetic and paramagnetic steady states. Our results suggest the occurence of first-order phase transitions between the above-mentioned phases at low temperatures and large random-field intensities $h_{o}$, for some small values of the width $\sigma$. By means of finite size scaling, we estimate the critical exponents in the low-field region, where we have continuous phase transitions. In addition, we show a sketch of the phase diagram of the model for some values of $\sigma$.Comment: 13 pages, 9 figures, accepted for publication in JSTA

Pinturas murales de la casa de Ariadna (Pompeya, Italia): un estudio multidisciplinar de su estado actual enfocado a una futura restauración y conservación preventiva

[EN] This paper deals with the development of a multidisciplinary study on the current state of conservation of Ariadne’s house (Pompeii, Italy), a domus of great archaeological value. The aim of this study is to undertake the preventive conservation actions required and increase the knowledge about its conservation and to generate discussions and points of view for a future restoration. Environmental studies, electromagnetic radiation measurements, study of materials and a photographical study were carried out. Those studies revealed that the rooftops covering the analyzed rooms resulting in adverse weather conditions causing grave damage to the conservation of the wall paintings. Thus, between 2009-2010 the rooftops were changed and new environmental studies were conducted. Studies of materials showed that the paintings match in execution and composition with those reported by other authors. The salts from modern mortars from previous restorations were affecting frescoes, also it is described a thin grayish surface layer from environmental contaminants.[ES] Este trabajo desarrolla un estudio multidisciplinar sobre el actual estado de conservación de la casa de Ariadna (Pompeya, Italia), domus de gran valor arqueológico. El objetivo es aumentar el conocimiento del estado actual de conservación de la casa para la discusión de una futura restauración. Para ello se realizaron estudios ambientales, mediciones de radiación electromagnética, estudio de materiales y un estudio fotográfico. Los estudios revelaron que los tejados que cubrían las salas analizadas estaban originando unas condiciones climatológicas adversas que se traducían en un grave daño para la conservación de las pinturas murales. Entre 2009-2010 se cambiaron las cubiertas y los estudios ambientales fueron repetidos. Los estudios de materiales demostraron que las pinturas coinciden en ejecución y composición con las señaladas por otros autores. Las sales procedentes de morteros modernos de anteriores restauraciones afectaban a las pinturas, también se describe una fina capa superficial de tonalidad grisácea procedente de contaminantes ambientales.This work was partially supported by the Spanish "Ministerio de Ciencia e Innovacion" under projects HAR2010-21944-C02-01 and HAR2010-21944-C02-02. The authors are grateful to J. Minguez for his English grammar corrections.Pérez García, MDC.; García Diego, FJ.; Merello Giménez, P.; D'antoni, P.; Fernández Navajas, A.; Ribera I Lacomba, A.; Ferrazza, L.... (2013). Ariadne's house (Pompeii, Italy) wall paintings: A multidisciplinary study of its present state focused on a future restoration and preventive conservation. Materiales de Construcción. 63(311):449-467. https://doi.org/10.3989/mc.2012.00812S4494676331

Ising critical behavior of a non-Halmiltonian lattice system

We study steady states in d-dimensional lattice systems that evolve in time by a probabilistic majority rule, which corresponds to the zero-temperature limit of a system with conflicting dynamics. The rule satisfies detailed balance for d=1 but not for d>1. We find numerically nonequilibrium critical points of the Ising class for d=2 and 3

Ariadne´s house (Pompeii, Italy) wall paintings: A multidisciplinary study of its present state focused on a future restoration and preventive conservation

Licencia Creative Commons Reconocimiento-No comercial 3.0 España.-- Revista del Instituto de Ciencias de la Construcción Eduardo Torroja.-- et al.[ES]: Este trabajo desarrolla un estudio multidisciplinar sobre el actual estado de conservación de la casa de Ariadna (Pompeya, Italia), domus de gran valor arqueológico. El objetivo es aumentar el conocimiento del estado actual de conservación de la casa para la discusión de una futura restauración. Para ello se realizaron estudios ambientales, mediciones de radiación electromagnética, estudio de materiales y un estudio fotográfico. Los estudios revelaron que los tejados que cubrían las salas analizadas estaban originando unas condiciones climatológicas adversas que se traducían en un grave daño para la conservación de las pinturas murales. Entre 2009-2010 se cambiaron las cubiertas y los estudios ambientales fueron repetidos. Los estudios de materiales demostraron que las pinturas coinciden en ejecución y composición con las señaladas por otros autores.[EN]: This paper deals with the development of a multidisciplinary study on the current state of conservation of Ariadne's house (Pompeii, Italy), a domus of great archaeological value. The aim of this study is to undertake the preventive conservation actions required and increase the knowledge about its conservation and to generate discussions and points of view for a future restoration. Environmental studies, electromagnetic radiation measurements, study of materials and a photographical study were carried out. Those studies revealed that the rooftops covering the analyzed rooms resulting in adverse weather conditions causing grave damage to the conservation of the wall paintings. Thus, between 2009-2010 the rooftops were changed and new environmental studies were conducted. Studies of materials showed that the paintings match in execution and composition with those reported by other authors. The salts from modern mortars from previous restorations were affecting frescoes, also it is described a thin grayish surface layer from environmental contaminants.Este trabajo fue parcialmente apoyado por el español “Ministerio de Ciencia e Innovación” en los proyectos HAR2010-21944-C02-01 y HAR2010-21944-C02-02.Peer reviewe

Approach to the Spanish continental Neogene synthesis and palaeoclimatic interpretation.

Peer reviewe