Diffusion in Fluctuating Media: The Resonant Activation Problem

We present a one-dimensional model for diffusion in a fluctuating lattice; that is a lattice which can be in two or more states. Transitions between the lattice states are induced by a combination of two processes: one periodic deterministic and the other stochastic. We study the dynamics of a system of particles moving in that medium, and characterize the problem from different points of view: mean first passage time (MFPT), probability of return to a given site ($P_{s_0}$), and the total length displacement or number of visited lattice sites ($\Lambda$). We observe a double {\it resonant activation}-like phenomenon when we plot the MFPT and $P_{s_0}$ as functions of the intensity of the transition rate stochastic component.Comment: RevTex, 15 pgs, 8 figures, submitted to Eur.Phys.J.

Bulk Mediated Surface Diffusion: The Infinite System Case

An analytical soluble model based on a Continuous Time Random Walk (CTRW) scheme for the adsorption-desorption processes at interfaces, called bulk-mediated surface diffusion, is presented. The time evolution of the effective probability distribution width on the surface is calculated and analyzed within an anomalous diffusion framework. The asymptotic behavior for large times shows a sub-diffusive regime for the effective surface diffusion but, depending on the observed range of time, other regimes may be obtained. Montecarlo simulations show excellent agreement with analytical results. As an important byproduct of the indicated approach, we present the evaluation of the time for the first visit to the surface.Comment: 15 pages, 7 figure

Invited review: KPZ. Recent developments via a variational formulation

Recently, a variational approach has been introduced for the paradigmatic Kardar--Parisi--Zhang (KPZ) equation. Here we review that approach, together with the functional Taylor expansion that the KPZ nonequilibrium potential (NEP) admits. Such expansion becomes naturally truncated at third order, giving rise to a nonlinear stochastic partial differential equation to be regarded as a gradient-flow counterpart to the KPZ equation. A dynamic renormalization group analysis at one-loop order of this new mesoscopic model yields the KPZ scaling relation alpha+z=2, as a consequence of the exact cancelation of the different contributions to vertex renormalization. This result is quite remarkable, considering the lower degree of symmetry of this equation, which is in particular not Galilean invariant. In addition, this scheme is exploited to inquire about the dynamical behavior of the KPZ equation through a path-integral approach. Each of these aspects offers novel points of view and sheds light on particular aspects of the dynamics of the KPZ equation.Comment: 16 pages, 2 figure

Bulk Mediated Surface Diffusion: Finite System Case

We address the dynamics of adsorbed molecules (a fundamental issue in surface physics) within the framework of a Master Equation scheme, and study the diffusion of particles in a finite cubic lattice whose boundaries are at the $z=1$ and the $z=L$ planes where $L = 2,3,4,...$, while the $x$ and $y$ directions are unbounded. As we are interested in the effective diffusion process at the interface $z = 1$, we calculate analytically the conditional probability for finding the system on the $z=1$ plane as well as the surface dispersion as a function of time and compare these results with Monte Carlo simulations finding an excellent agreement.Comment: 19 pages, 8 figure

Vanishing DC holographic conductivity from a magnetic monopole condensate

We show how to obtain a vanishing DC conductivity in 3-dimensional strongly coupled QFT's using a massive 2-form field in the bulk that satisfies a special kind of boundary condition. The real and imaginary parts of the AC conductivity are evaluated in this holographic setup and we show that the DC conductivity identically vanishes even for an arbitrarily small (though nonzero) value of the 2-form mass in the bulk. We identify the bulk action of the massive 2-form with an effective theory describing a phase in which magnetic monopoles have condensed in the bulk. Our results indicate that a condensate of magnetic monopoles in a 4-dimensional bulk leads to a vanishing DC holographic conductivity in 3-dimensional strongly coupled QFT's.Comment: 24 pages, 2 figures, accepted for publication in JHE

Built Heritage Research and History of Architecture: Light and Acoustic in the Cistercian Monastic Church of S. Bento de Cástris (Portugal)

The research on the Cistercian legacy in Portugal is an innovative multidisciplinary study. Consequently, the results achieved in this research have many different approaches: the former monasteries and their architecture are the main subjects concerning morphology, architectonic rehabilitation but also acoustics, thermal comfort, or natural light. This research, carried out at the Department of Civil Engineering and Architecture of the University of Beira Interior (DECA-UBI), was developed in connection with two other research centres - Lab2PT (Landscape, Heritage and Territory Laboratory) and CIDEHUS (Interdisciplinary Centre for History, Culture and Societies). In 2015, the curriculum of the Integrated Master Degree in Architecture of the University of Beira Interior underwent revision. Consequently, it was needed to allocate more time to the teaching of History of Architecture and the requirement to assign specific syllabus to the Portuguese History of Architecture, which is emphasized by the specific and multidisciplinary research performed linking with other sciences of engineering. The natural light in the Cistercian churches is closely linked not only with the liturgical requirements at the officium but also with the canonical hours based on the "ora et labora" dictated by the Rule of St. Benedict. The Cistercian Monastery of São Bento de Cástris (13th-19th centuries), in Évora, Portugal, includes a church, at the south-eastern corner. This church presents an unusual space setting with two choirs which seems to favour different positions for coral groups supporting liturgical and musical expression activities within the research scope of a Research Project. As the light in the Cistercian Monasteries, mainly, in their churches, is mostly related to the fulfilment of liturgical needs, this paper analyses the relationship between daylight conditions within the monastic choirs located within the monastic church. The chant was a very important way of oration and thus of the liturgy. This was the ORFEUS Project – “The Tridentine Reform and music in the cloistral silence: The Monastery of S. Bento de Cástris” which was based on a multidisciplinary approach around the Tridentine Reform with reflexes in the musical Cistercian feminine matrix between the 16th and 18th centuries on Cistercian Monasteries. This paper describes the objectives and methodology applied to the case study thus linking Built Heritage Research and History of Architecture, i.e., Research and Education.info:eu-repo/semantics/publishedVersio

Essence of Daylight in the Cistercian Monastic Church of S. Bento de Cástris, Évora, Portugal

Natural light in the Cistercian churches is closely linked not only with the liturgical requirements at the “officium” but also with the canonical hours based on the "ora et labora" dictated by the Rule of St. Benedict. The Cistercian architecture, in its beginnings (12th century forward) is characterized by austerity, simplicity and the play of light and shadow that gives value to the monastic architectural space itself, making it perfect for a contemplative experience. In the Cistercian Monastery the church is the central piece of the monastic building. Nave, transept and apse are the main architectural components to which is added the choir. This paper contextualizes the importance and close connections of natural light, within the Cistercian Monasteries architecture. Thus the essence of daylight is analyzed within the Church of the Monastery of S. Bento de Cástris, in Évora, Portugal. This former Monastery (13th - 19th centuries) includes the church, at the southeastern corner which has not only a high choir, but also a low lateral choir (within the presbytery). Its unchanged exterior walls are made of solid masonry. Although the function of the walls is primarily structural, the windows allow the daylight to penetrate the space of the church. The church has two external façades facing northeast and southeast. The combined orientation effect of the church’s main axis and the sun trajectory determines how the sunlight reaches the interior of this architectural structure. This study presents the qualitative and quantitative analysis of the luminous environment in the church of S. Bento de Cástris, being the first based on the authors’ perception of the effect of the daylight within the different areas of the enclosed space. The appreciation of the spatial experiences was supported by quantitative daylight simulations that were conducted in selected areas within the space. With this paper is intended to contribute to the debate about the specificity of daylight, in the context of Cistercian architecture.info:eu-repo/semantics/publishedVersio

Operación cesárea

ResumenLa operación cesárea permite el nacimiento por vía abdominal. De origen no claro, su indicación es para condiciones extremas a indicaciones consideradas como relativas. Su incidencia ha aumentado significativamente en los últimos años con una gran variabilidad de tasas entre países e instituciones. Las causas de este aumento son diversas. Se han descrito múltiples técnicas quirúrgicas. En el presente artículo se describen los aspectos técnicos de su ejecución así como las indicaciones más frecuentes.SummaryCesarean section allows the birth by histeroromy performed through the abdomen. Of unclear origin, its original indications were very few. Its incidence has increased significantly in recent years with a large variability of rates between countries and institutions. The causes of this increase are varied. Multiple surgical techniques have been described. The technical aspects of its implementation as well as the most frequent indications are described

Technologies for reusing, recycling and energetic valorization of tires in Brazil

Os pneus usados estão se tornando um problema mundial. O descarte de pneus cresce ano após ano em todo o mundo. Pouca importância foi dada ao descarte de pneus em muitos países. No Brasil, em 1999, foi aprovada a Resolução nº 258/99 do CONAMA (Conselho Nacional do Meio Ambiente) que instituiu a responsabilidade do produtor e do importador pelo ciclo total do produto, ou seja, a coleta, o transporte e a disposição final. Desde 2002, os fabricantes e importadores de pneus devem coletar e dar a destinação final para os pneus usados. Segundo essa lei, os distribuidores, revendedores, reformadores e consumidores finais são co-responsáveis pela coleta dos pneus servíveis e inservíveis, os quais devem colaborar com a coleta. Neste trabalho serão apresentadas as tecnologias utilizadas no Brasil para a reutilização, reciclagem e valorização energética, além de um fluxograma do processo de logística reversa dos pneus novos e usados, dados estatísticos dos canais de distribuição, objetivo da reciclagem e a disposição final, no período de 2002 a 2006. Em 2006, foram reciclados 240,62 mil toneladas de pneus inservíveis, o equivalente a 48,12 milhões de pneus de automóvel. As atividades de laminação, trituração e fabricação de artefatos de borracha representaram 50,02% do total destinado, o co-processamento em fornos de clínquer representou 35,73%, a regeneração de borracha sintética representou 13,22% e a extração e tratamento de minerais 1,03%.Used tires have become a worldwide problem. The discarding of tires rises year after year all over the world. So far little importance has been given to the discarding of tires in many countries. In 1999, the CONAMA (National Council for the Environment) resolution 258/99 made the producer or importer as responsible for the total cycle of the product in Brazil, including the means of collection, transportation and final destination to the product. Since 2002, the manufacturers and importers of tires must collect and give the final destination to the used tires. The distributors, retailers, re-modelers and final consumers are co-responsible for the collection of the used or unserviceable tires. In this study we review the technologies for reusing, recycling and energetic valorization of tires, in addition to presenting a flowchart of the reverse logistic process for new and used tires. Also included are statistical data of distribution channels, recycling goals and final destination for the used tires in the period from 2002 to 2006. In 2006, 240.62 thousand tons of unserviceable tires were recycled, which correspond to 48.12 million of automobile tires. The activities of laminating, grinding and manufacturing of rubber artifacts represented 50.02% of the total; the co-processing in clinker ovens represented 35.73%; the synthetic rubber regeneration represented 13.22% while 1.03% was used in the extraction and treatment of minerals