A variational model for fracture and debonding of thin films under in-plane loadings

We study fracture and debonding of a thin stiff film bonded to a rigid substrate through a thin compliant layer, introducing a two-dimensional variational fracture model in brittle elasticity. Fractures are naturally distinguished between transverse cracks in the film (curves in 2D) and debonded surfaces (2D planar regions). In order to study the mechanical response of such systems under increasing loads, we formulate a dimension-reduced, rate-independent, irreversible evolution law accounting for both transverse fracture and debonding. We propose a numerical implementation based on a regularized formulation of the fracture problem via a gradient damage functional, and provide an illustration of its capabilities exploring complex crack patterns, showing a qualitative comparison with geometrically involved real life examples. Moreover, we justify the underlying dimension-reduced model in the setting of scalar-valued displacement fields by a rigorous asymptotic analysis using Γ-convergence, starting from the three-dimensional variational fracture (free-discontinuity) problem under precise scaling hypotheses on material and geometric parameters. © 2014 Elsevier Ltd

Local invertibility in Sobolev spaces with applications to nematic elastomers and magnetoelasticity

We define a class of deformations in W^1,p(\u3a9,R^n), p>n 121, with positive Jacobian that do not exhibit cavitation. We characterize that class in terms of the non-negativity of the topological degree and the equality between the distributional determinant and the pointwise determinant of the gradient. Maps in this class are shown to satisfy a property of weak monotonicity, and, as a consequence, they enjoy an extra degree of regularity. We also prove that these deformations are locally invertible; moreover, the neighbourhood of invertibility is stable along a weak convergent sequence in W^1,p, and the sequence of local inverses converges to the local inverse. We use those features to show weak lower semicontinuity of functionals defined in the deformed configuration and functionals involving composition of maps. We apply those results to prove existence of minimizers in some models for nematic elastomers and magnetoelasticity

Charged Annular Disks and Reissner-Nordstr\"{o}m Type Black Holes from Extremal Dust

We present the first analytical superposition of a charged black hole with an annular disk of extremal dust. In order to obtain the solutions, we first solve the Einstein-Maxwell field equations for sources that represent disk-like configurations of matter in confomastatic spacetimes by assuming a functional dependence among the metric function, the electric potential and an auxiliary function,which is taken as a solution of the Laplace equation. We then employ the Lord Kelvin Inversion Method applied to models of finite extension in order to obtain annular disks. The structures obtained extend to infinity, but their total masses are finite and all the energy conditions are satisfied. Finally, we observe that the extremal Reissner-Nordstr\"{o}m black hole can be embedded into the center of the disks by adding a boundary term in the inversion.Comment: 17 revtex pages, 8 eps figure

Fotosensibilidad experimental en bovinos en un área tropical utilizando el hongo Pithomyces chartarum.

El objetivo fue reproducir experimentalmente casos clínicos de fotosensibilización utilizando el hongo Pithomyces chartarum presente naturalmente en potreros de Brachiaria decumbens pero aumentando artificialmente la cantidad de esporas disponibles. El estudio se realizó en el Centro Nacional de Investigaciones Agropecuarias Carimagua, ICA-CIAT en los Llanos Orientales de Colombia localizado a 150-175 m.s.n.m. y una temperatura promedia de 24 grados centígrados. Se escogieron 2 grupos de animales para el estudio. El primer grupo de 15 novillas de 18 meses de edad, se asignó a un potrero de 7 ha con un pasto establecido de Brachiaria decumbens. Cuatro hectáreas en este potrero fueron utilizadas para hacer aspersión de esporos del hongo Pithomyces chartarum de un cultivo en medio artificial. El segundo grupo de 12 novillas se asignó a un potrero de 5 ha de Brachiaria decumbens separado y distante del primer grupo. A este potrero no se le hizo ninguna aplicación de hongo. En el potrero inoculado con esporas del hongo apareció un animal con lesiones cutáneas de fotosensibilización a los 32 días después de iniciado el pastoreo del potrero contaminado y cuatro animales desarrollaron enfermedad sub-clínica. En el potrero que no recibió inoculación del hongo no se observaron animales afectados por el hongo. De esas observaciones podría esbozarse la hipótesis de que bajo condiciones naturales los brotes de fotosensibilización ocurren algún tiempo después de que las condiciones climáticas favorables para el desarrollo del hongo sobre el pasto hayan permitido la multiplicación del hongo, y la ingestión de suficiente toxina por los animales para producir la afecciónGanado de leche-Ganadería lech

Econometric analysis of the industrial growth determinants in Colombia

An econometric study is carried out using a panel data model with fixed effects to identify the industrial development determinants in Colombia during the term 2005–2015. The database used in the study corresponds to World Bank and the Colombian state. The determinants of industrial growth identified at the theoretical level that allow the enhancement of productive capacities to face foreign competition in Colombia are: innovation; networks of innovations and knowledge among companies and organizations; the interest rate; the capital-product ratio, the unit labor cost; and the exchange rate. The amount invested in scientific, technological and innovation activities by industrial group is the only variable that is not significant in the model

Citescore of publications indexed in Scopus: an implementation of panel data

This article is intended to establish the variables that explain the behavior of the CiteScore metrics from 2014 to 2016, for journals indexed in Scopus in 2017. With this purpose, journals with a CiteScore value greater than 11 were selected in any of the periods, that is to say, 133 journals. For the data analysis, a model of standard corrected errors for panel was used, from which a coefficient of determination of 77% was obtained. From the results, it was possible to state that journals of arts and humanities; business; administration and accounting; economics, econometrics, and finance; immunology and microbiology; medicine and social sciences, have the greatest impact.Corporación Universitaria Minuto de Dios, Fundación Universitaria Konrad Lorenz, Universidad de La Habana, Universidad de la Costa

Aspectos epidemiológicos de la fotosensibilización hepatotóxica asociada al pastoreo de Brachiaria decumbens en los Llanos Orientales de Colombia.

Se describen las características clínicas y epidemiológicas de 43 casos del síndrome de fotosensibilización en bovinos, asociado al consumo de Brachiaria decumbens, los cuales ocurrieron durante un período de 4 años. El síndrome se presenta con preferencia en animales jóvenes, hasta los 24 meses de edad y en épocas de transición lluvias-sequía o viceversa. Se reconocen 2 cuadros clínicos, uno con edemas y el otro con necrosis de piel. Las lesiones macro y microscópicas corresponden a una afección hepatotóxica. La observación de un brote en ovinos de la región en similares circunstancias e idéntico proceso clínico, establece una semejanza del síndrome con el eczema facial de las ovejas en Nueva Zelandi

Building a circular supply chain:Achieving resilient operations with the circular economy

This paper highlights the fundamental contribution that supply chain professionals can make to the transition to a circular economy. It aims to provide a general understanding of how the circular economy and supply chain management fields are related to one another. By exploring the concept of a circular supply chain, the paper illustrates the role of supply chain professionals in operationalising circular economy initiatives within their organisations, as well as the opportunities and challenges they may encounter along the way. The paper also provides initialrecommendations for and examples of companies overcoming some of these challenges, based on the experiences of supply chain professionals involved in the research