123 research outputs found
Investigación sobre morteros y sus tratamientos para su restauración en el Retablo del Altar Mayor de la Basílica del Pilar
The altarpiece of the Assumption of Mary is located in the High Altar of the Pilar Basilica in Zaragoza and is one of the most important works of the Spanish Artistic Heritage.
The work, sculptured in alabaster, was carried out between 1509 and 1518 by Damián Forment.
The present paper covers the guidelines for the design of repair mortars used to restore the altarpiece. They are based on compatibility criteria with the existing materials and treatments in the altarpiece, according to research carried out during the recent works of cleaning and restoration.
During the previous research, the composition of the original mortars was tested, the aggregate granulometry, and the composition of the organic additives used. The patina of the altarpiece was also analyzed and identified.
The original mortars were made up of a mixture of gypsum and lime with the addition of oil or fats. In many cases various types of fibre were detected in the mortar, used to improve its mechanical characteristics.
The repair mortars were designed with a composition similar to the originals, with a mixture of gypsum and lime, and their compatibility with the alabaster was studied, while also optimizing the granulometry of the aggregates used.El retablo de la Asunción de María está situado en el Altar Mayor de la Basílica del Pilar en Zaragoza y es una de las grandes obras del Patrimonio artístico español. La obra, esculpida en alabastro, fue realizada entre 1509 y ¡518 por Damián Forment.
En este trabajo se recogen las directrices para el diseño de los morteros de reparación utilizados en la restauración del retablo. Se basaron en criterios de compatibilidad de los materiales y tratamientos existentes en el retablo, según la investigación realizada durante las obras de la última actuación realizada para la limpieza y restauración.
En la investigación realizada se comprobó la composición de los morteros originales, la granulometría de los áridos empleados, así como la composición de los aditivos orgánicos utilizados. Igualmente se analizó e identificó la pátina del retablo.
Los morteros originales estaban compuestos por una mezcla de yeso y cal con adición de aceite o grasa. En muchos casos se detectaron diversos tipos de fibras en la masa de los morteros, utilizadas para mejorar sus características mecánicas.
Los morteros de reparación se han diseñado con una composición similar a la de los antiguos, con una mezcla de yeso y cal, y se estudió su compatibilidad con el alabastro, optimizándose igualmente la granulometría de los áridos a utilizar
Universal relaxation function in nonextensive systems
We have derived the dipolar relaxation function for a cluster model whose
volume distribution was obtained from the generalized maximum Tsallis
nonextensive entropy principle. The power law exponents of the relaxation
function are simply related to a global fractal parameter and for
large time to the entropy nonextensivity parameter . For intermediate times
the relaxation follows a stretched exponential behavior. The asymptotic power
law behaviors both in the time and the frequency domains coincide with those of
the Weron generalized dielectric function derived from an extension of the Levy
central limit theorem. They are in full agreement with the Jonscher
universality principle. Moreover our model gives a physical interpretation of
the mathematical parameters of the Weron stochastic theory and opens new paths
to understand the ubiquity of self-similarity and power laws in the relaxation
of large classes of materials in terms of their fractal and nonextensive
properties.Comment: Two figures. Submitted for publicatio
A Bethe lattice representation for sandpiles
Avalanches in sandpiles are represented throughout a process of percolation
in a Bethe lattice with a feedback mechanism. The results indicate that the
frequency spectrum and probability distribution of avalanches resemble more to
experimental results than other models using cellular automata simulations.
Apparent discrepancies between experiments are reconciled. Critical behavior is
here expressed troughout the critical properties of percolation phenomena.Comment: 5 pages, 4 figures, submitted for publicatio
Four-color single-molecule imaging with engineered tags resolves the molecular architecture of signaling complexes in the plasma membrane
New model for surface fracture induced by dynamical stress
We introduce a model where an isotropic, dynamically-imposed stress induces
fracture in a thin film. Using molecular dynamics simulations, we study how the
integrated fragment distribution function depends on the rate of change and
magnitude of the imposed stress, as well as on temperature. A mean-field
argument shows that the system becomes unstable for a critical value of the
stress. We find a striking invariance of the distribution of fragments for
fixed ratio of temperature and rate of change of the stress; the interval over
which this invariance holds is determined by the force fluctuations at the
critical value of the stress.Comment: Revtex, 4 pages, 4 figures available upon reques
Infinite ergodic theory and Non-extensive entropies
We bring into account a series of result in the infinite ergodic theory that
we believe that they are relevant to the theory of non-extensive entropie
Exact correlation functions of Bethe lattice spin models in external fields
We develop a transfer matrix method to compute exactly the spin-spin
correlation functions of Bethe lattice spin models in the external magnetic
field h and for any temperature T. We first compute the correlation function
for the most general spin - S Ising model, which contains all possible
single-ion and nearest-neighbor pair interactions. This general spin - S Ising
model includes the spin-1/2 simple Ising model and the Blume-Emery-Griffiths
(BEG) model as special cases. From the spin-spin correlation functions, we
obtain functions of correlation length for the simple Ising model and BEG
model, which show interesting scaling and divergent behavior as T approaches
the critical temperature. Our method to compute exact spin-spin correlation
functions may be applied to other Ising-type models on Bethe and Bethe-like
lattices.Comment: 19 page
Comparison between Spanish young and elderly people evaluated using Rivermead Behavioural Memory Test
The first objective of this work was to compare scores obtained in the daily memory function between young and elderly people, and to check whether there are differences between the groups for each of the profile scores obtained in the memory test. A second aim of this paper is to study the relationship between everyday memory and age, while controlling for gender and educational level. The total and profile scores obtained in the Rivermead Behavioural Memory Test were compared in a sample of 60 young and 120 elderly people from Valencia (Spain). Results showed significant differences between the two groups: those between 18 and 30 years obtained a higher average than those over 65. Once the group comparison was controlled for gender and educational level, the statistical effect of age group disappeared. The non-significant effect of group can not be explained by the introduction of gender, because both its main effect and the interaction were not statistically significant. However, educational level had a statistically significant effect which may explain the non-significant effect of group in this new analysis. The main conclusion is the need to carefully control for educational level in all studies related with everyday memory and ageing, as the differences found could be due to generational differences more than to biological deterioratio
Vertical volumetric distribution of an axial fan sprayer on the Brevipalpus phoenicis control
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