Diffractive photoproduction of heavy quarks in hadronic collisions

In this letter we study the diffractive photoproduction of heavy quarks in hadronic (pp/pA/AA) interactions for Tevatron and LHC energies. The integrated cross section and rapidity distribution for the process h_1 h_2 --> h_1 h_2 QQBAR (h_i = p,A and Q = c,b) are estimated using the Color Glass Condensate (CGC) formalism. Our results indicate that this production channel has larger cross sections than the competing reactions of double diffractive production and coherent AA reactions initiated by two-photon collisions.Comment: 4 pages, 2 figures, 1 table. Version to be published in Physical Review

Photoproduction of ρ0\rho^0 mesons in ultraperipheral heavy ion collisions at energies available at the BNL Relativistic Heavy Ion Collider (RHIC) and CERN Large Hadron Collider (LHC)

We investigate the photoproduction of $\rho$ mesons in ultraperipheral heavy ion collisions at RHIC and LHC energies in the dipole approach and within two phenomenological models based on the the Color Glass Condensate (CGC) formalism. We estimate the integrated cross section and rapidity distribution for meson production and compare our predictions with the data from the STAR collaboration. In particular, we demonstrate that the total cross section at RHIC is strongly dependent on the energy behavior of the dipole-target cross section at low energies, which is not well determined in the dipole approach. In contrast, the predictions at midrapidities at RHIC and in the full rapidity at LHC are under theoretical control and can be used to test the QCD dynamics at high energies.Comment: 6 pages, 5 figures, 1 table. Improved version to be published in Physical Review

Texture descriptor combining fractal dimension and artificial crawlers

Texture is an important visual attribute used to describe images. There are many methods available for texture analysis. However, they do not capture the details richness of the image surface. In this paper, we propose a new method to describe textures using the artificial crawler model. This model assumes that each agent can interact with the environment and each other. Since this swarm system alone does not achieve a good discrimination, we developed a new method to increase the discriminatory power of artificial crawlers, together with the fractal dimension theory. Here, we estimated the fractal dimension by the Bouligand-Minkowski method due to its precision in quantifying structural properties of images. We validate our method on two texture datasets and the experimental results reveal that our method leads to highly discriminative textural features. The results indicate that our method can be used in different texture applications.Comment: 12 pages 9 figures. Paper in press: Physica A: Statistical Mechanics and its Application

Cómics : investigación de conceptos y de términos paleontológicos, y uso como recurso didáctico en la Educación Primaria

Este trabajo investiga el modo en que los cómics, como recurso didáctico, tratan los contenidos paleontológicos. Tras un sistemático análisis, resultó evidente que esos conceptos están presentes en los cómics con aciertos pero también con muchos errores y equivocaciones, que no pueden ser ignorados. Los maestros deberían estar atentos a los cómics y usarlos en su práctica educativa.This study intended to verify what paleontological contents could be found in cartoons and their use as didactic material. After a systematized reading, the results showed that the concepts of Paleontology present in this media are a more wrong than correct fact which cannot be ignored. Therefore, teachers should pay attention and adopt it as didactic material

Instruments de ténèbres de Nancy Huston : entre la scordatura et la sonate

Instruments des Ténèbres (1996) de Nancy Huston raconte deux histoires qui se ressemblent étrangement — celle de Nadia au XXe siècle et celle de Barbe Durand à la fin du XVIIe siècle. L’écriture du carnet intime (« Le Carnet scordatura ») de la première est souvent interrompue par celle de son roman (« Sonate de la résurrection »), l'histoire tragique de Barbe et de son frère qui s'inspire d'un fait réel. Progressivement ces deux récits se font écho, s’entremêlent et la confrontation à la traversée continue du temps aboutit à une réflexion vigoureuse mise en abyme sur l’écriture pleine de références intertextuelles Nodier, Michelet, Virginia Woolf. Dans une toute première lecture du roman, prenant appui sur des concepts de Roland Barthes – l’âge mutatif et le milieu de la vie –,on propose une discussion sur certains aspects de la temporalité dans ce récit à deux voix.Fil: Machado, Maristela Gonçalves Sousa. Universidade Federal de Pelotas

La emigración portuguesa hacia Francia en la segunda mitad del siglo XX : breve caracterización

La emigración a Francia durante la segunda mitad del siglo XX representa uno de los mayoress movimientos de población del que se tenga memoria en la larga historia de Portugal. ¿Como enmarcar semejante boom? ¿Qué factores lo propiciaron? ¿Cuales fueron sus peculiaridades y sus consecuencias? ¿qué relaciones se establecieron, a nivel social y político, entre el país y sus emigrantes? Tales son las principales cuestiones que el presente artículo se propone abordar.The emigration to France in the second half of the twentieth century represents one of the major populations movements that we have memory in the history of Portugal. How can we frame that boom? Which factors propitiate it? Which characteristics specify it? Which consequences followed up? What relations were established, in a social and political level, between the country and its emigrants? There are the main questions that we want to study with this pape

Influence of materials’ hygroscopicity in the control of relative humidity and temperature of old buildings

The comfort of buildings indoor environment and materials durability are severally affected by peaks of temperature and relative humidity (RH) in interior of buildings and therefore they should be controlled and damped. The presence of people inside buildings as well as artificial illumination and all kind of equipment cause a releasing of moisture to environment, which originates an increment of its relative humidity. The occupants, artificial illumination and equipment also originate a temperature raising depending the occupants’ activity and the quantity and power of illumination and equipment. In order to reach an interior environment with values of relative humidity and temperature that ensure acceptable conditions to human health and materials longevity, it is important to install measures to control them. These measures can be active or passive if, respectively, they intend to remediate the unacceptable values of RH or temperature or if those acceptable values are achieved by installing coating materials capable of control both parameters during all seasons. If the materials are able to control temperature and relative humidity of indoor, so they contribute to improving thermal and hygroscopic inertia of buildings. Old buildings are characterized by having high thermal inertia and this means that its interior environment has a significant gap in relation to the exterior one, with regard to temperature. However, the temperature also affects relative humidity once both have an inverse relation of proportionality. This makes that it is important to damp relative humidity of old buildings indoor that would not have those values if it did not have high thermal inertia. This fact makes that be important to control relative humidity and temperature of old buildings indoor, preferably using passive measures, to preserve some very important works of art, books or documents, in case of being a museum or an archive. To control temperature and relative humidity of interior environment it is necessary to choose the best coating materials that can provide to buildings higher hygroscopic and thermal inertia. For that, it is indispensable to make correct materials characterization in order to discover their real behavior and, with base on those characteristics obtained experimentally, they could be properly chosen to be applied in buildings. In consequence of that, in the present dissertation, the materials behavior at different ranges of RH was analyzed as well as the time of exposition to those controlled environments. For that, it was chosen to make the tests of adsorption/desorption isotherm, Moisture Buffering Value (MBV), moisture permeability, thermal conductivity and response time. Additionally, the response of materials to certain interior environment was determined, by making a hygrothermal simulation in transient regime, with recourse to software Wufi Plus