On the consistency of universally non-minimally coupled f(R,T,RμνTμν)f(R,T,R_{\mu\nu}T^{\mu\nu}) theories

We discuss the consistency of a recently proposed class of theories described by an arbitrary function of the Ricci scalar, the trace of the energy-momentum tensor and the contraction of the Ricci tensor with the energy-momentum tensor. We briefly discuss the limitations of including the energy-momentum tensor in the action, as it is a non fundamental quantity, but a quantity that should be derived from the action. The fact that theories containing non-linear contractions of the Ricci tensor usually leads to the presence of pathologies associated with higher-order equations of motion will be shown to constrain the stability of this class of theories. We provide a general framework and show that the conformal mode for these theories generally has higher-order equations of motion and that non-minimal couplings to the matter fields usually lead to higher-order equations of motion. In order to illustrate such limitations we explicitly study the cases of a canonical scalar field, a K-essence field and a massive vector field. Whereas for the scalar field cases it is possible to find healthy theories, for the vector field case the presence of instabilities is unavoidable.Comment: Minor changes, version published matching Phys. Rev. D 91 (2015) 104003. 15 pages, no figure

Generación automática de un índice de recursos bioinformáticos a partir de la literatura científica

En los últimos años se ha producido un aumento en el número de recursos bioinformáticos de carácter público accesibles a través de Internet. Éstos proporcionan diversas herramientas y bases de datos a la comunidad científica, facilitando así las diferentes tareas que surgen durante la investigación biomédica. Como ejemplo, estas tareas incluyen búsquedas en bases de datos, alineamiento y búsqueda de secuencias genéticas, anotación y visualización de proteínas, etc. La evolución en la representación de datos biológicos y en la implementación de herramientas para el análisis y almacenamiento de los mismos ha dado como resultado la proliferación de numerosos estándares de representación e interfaces de análisis y procesamiento. La complejidad a la hora de recuperar la información proporcionada por estos datos y navegar por distintas redes para su análisis constituye un “cuello de botella” para los bioinformáticos y una barrera para los investigadores que no poseen una formación en el campo de la informática. Llegados a este punto, la integración de todos los datos y herramientas bioinformáticas existentes es vital, pero no ha empezado a ser tratada de manera exhaustiva hasta los últimos años

Automatic learning of gait signatures for people identification

This work targets people identification in video based on the way they walk (i.e. gait). While classical methods typically derive gait signatures from sequences of binary silhouettes, in this work we explore the use of convolutional neural networks (CNN) for learning high-level descriptors from low-level motion features (i.e. optical flow components). We carry out a thorough experimental evaluation of the proposed CNN architecture on the challenging TUM-GAID dataset. The experimental results indicate that using spatio-temporal cuboids of optical flow as input data for CNN allows to obtain state-of-the-art results on the gait task with an image resolution eight times lower than the previously reported results (i.e. 80x60 pixels).Comment: Proof of concept paper. Technical report on the use of ConvNets (CNN) for gait recognition. Data and code: http://www.uco.es/~in1majim/research/cnngaitof.htm

Flutter Stability Analysis of an Aircraft Wing as a Function of Damping Ratio

This report provides insight into flutter stability analysis as a function of damping ratio. Flutter, an unstable self-excited vibration in which the structure extracts energy from the air stream and often results in catastrophic structural failure, is analyzed as dynamic instability, which may eventually result in stall or buffeting conditions or classical bending and torsion coupling actions. These couplings occur when the aerodynamic forces associated with motion in two modes of vibration cause the modes to couple in an unfavorable manner. The characteristic equation will be analyzed and derived in order to study stability and its relationship with the damping ratios of the aircraft wing. Analytical analysis of different mode shapes will be carried out by means of applying Newton’s equation of motion and time-dependent boundary conditions. Underdamped, critically damped, over-damped and flutter diagrams will be obtained for different damping ratios. Furthermore, these diagrams will be compared with analytical derivations. Those results indicate stability dependence on damping ratio as it is basically a free vibration problem. Comparison between different models shows accurate results. Further research is focused on considering and proving detailed results on experimental data on lab

Surface magnetism in ZnO/Co3O4 mixtures

We recently reported the observation of room temperature ferromagnetism in mixtures of ZnO and Co3O4 despite the diamagnetic and antiferromagnetic character of these oxides respectively. Here we present a detailed study on the electronic structure of this material in order to account for this unexpected ferromagnetism. Electrostatic interactions between both oxides lead to a dispersion of Co3O4 particles over the surface of ZnO larger ones. As a consequence, the reduction of Co+3 to Co2+ at the particle surface takes place as evidenced by XAS measurements and optical spectrocopy. This reduction allows to xplain the observed ferromagnetic signal within the well established theories of magnetism.Comment: Accepted in Journal of Applied Physic

How small and medium-sized enterprises can uptake the sustainable development goals through a cluster management organization: a case study

Even though many small and medium-sized enterprises (SMEs) realize the importance of the Sustainable Development Goals (SDGs) for their sustainable business development, they face difficulties when individually pursuing this target. This paper aims to provide cluster-based SMEs with a framework to facilitate the uptake of the SDGs through a cluster network model. By focusing on the case study of a furniture production Cluster Management Organization (CMO Habic a network-based approach to sustainability management is analyzed in order to integrate the SDGs framework into SMEs’ everyday language and day-to-day operations. Through a cluster model approach, industry-specific sustainability material issues are tackled jointly and with the aim of applying a common solution to a similar challenge, Lehi-ODS, an online sustainability management tool for SME self-evaluation, has been developed wherein the participating SMEs can gain an overarching knowledge about the UN 2030 Agenda, assess their own alignment with the SDGs and with respect to that of their peers, and prioritize initiatives to correctly deliver them. The main conclusion derived from the paper is that a CMO is deemed to be a valuable driver in identifying common sector-specific challenges of corporate sustainability and in addressing collectively the question of contributing to the SDGs