Pintura y Terror : Jacques-Louis David en 1793-1794

Entre 1793 y 1794, durante el llamado «Gran Terror», los retratos de los «mártires revolucionarios» de Jacques-Louis David han desarticulado las bases de la pintura de historia al eliminar la narración y el espacio de la perspectiva tal y como habían sido concebidos desde el Renacimiento. Este artículo indaga en este proceso a través del entramado político, social y religioso que se puso en marcha durante la República jacobina.Entre 1793 i 1794, durant l'anomenat «Gran Terror», els retrats dels «màrtirs revolucionaris» de Jacques-Louis David van desarticular les bases de la pintura d'història en eliminar la narració i l'espai de la perspectiva tal com havien estat concebuts des del Renaixement. Aquest article indaga en aquest procés a través de l'entramat polític, social i religiós que es va engegar durant la República jacobina.During the so-called "Reign of Terror" from 1793 to 1794, the portraits of "revolutionary martyrs" by Jacques-Louis David dismantled the foundations of history painting, thus erasing the principles of pictorial narrative and perspective existing since the Renaissance. The purpose of this paper is to explore this process through the political, social and religious framework constructed during the Jacobin Republic

Painting and Terror: Jacques-Louis David in 1793-1794

Entre 1793 i 1794, durant l’anomenat «Gran Terror», els retrats dels «màrtirs revolucionaris» de Jacques-Louis David van desarticular les bases de la pintura d’història en eliminar la narració i l’espai de la perspectiva tal com havien estat concebuts des del Renaixement. Aquest article indaga en aquest procés a través de l’entramat polític, social i religiós que es va engegar durant la República jacobina.During the so-called “Reign of Terror” from 1793 to 1794, the portraits of “revolutionary martyrs” by Jacques-Louis David dismantled the foundations of history painting, thus erasing the principles of pictorial narrative and perspective existing since theRenaissance. The purpose of this paper is to explore this process through the political, social and religious framework constructed during the Jacobin Republic

Antecedentes del comportamiento colaborativo en la empresa: el caso de los blogs corporativos. Antecedents of collaborative behavior in companies: an analysis of the use of corporate blogs

La implementación exitosa de herramientas colaborativas en las empresas exige de los empleados un comportamiento colaborativo adecuado. Este trabajo presenta una caracterización del compotamiento colaborativo a través del uso de blogs corporativos,identificando sus antecedentes y analizando la influencia relativa de éstos en el comportamiento colaborativo de 86 empleados del departamento de Sistemas de Información de una gran empresa industrial localizada en España. Los resultados indican que entre los antecedentes identificados, el altruismo,los objetos comunes y la confianza mutua predicen positivamente el comportamiento colaborativo,mientras que el sentdio de pertenecencia a una comunidad,la reputación y la reciprocidad no lo hacen

The zero-removing property in some Hilbert spaces of entire functions arising in sampling theory

In the topic of sampling in reproducing kernel Hilbert spaces, sampling in Paley–Wiener spaces is the paradigmatic example. A natural generalization of Paley–Wiener spaces is obtained by substituting the Fourier kernel with an analytic Hilbert-space-valued kernel K. Thus we obtain a reproducing kernel Hilbert space HKHK of entire functions in which the Kramer property allows to prove a sampling theorem. A necessary and sufficient condition ensuring that this sampling formula can be written as a Lagrange-type interpolation series concerns the stability under removal of a finite number of zeros of the functions belonging to the space HKHK; this is the so-called zero-removing property. This work is devoted to the study of the zero-removing property in HKHK spaces, regardless of the Kramer property, revealing its connections with other mathematical fields

Predicting academic performance with learning analytics in virtual learning environments: A comparative study of three interaction classifications

Learning analytics is the analysis of static and dynamic data extracted from virtual learning environments, in order to understand and optimize the learning process. Generally, this dynamic data is generated by the interactions which take place in the virtual learning environment. At the present time, many implementations for grouping of data have been proposed, but there is no consensus yet on which interactions and groups must be measured and analyzed. There is also no agreement on what is the influence of these interactions, if any, on learning outcomes, academic performance or student success. This study presents three different extant interaction typologies in e-learning and analyzes the relation of their components with students? academic performance. The three different classifications are based on the agents involved in the learning process, the frequency of use and the participation mode, respectively. The main findings from the research are: a) that agent-based classifications offer a better explanation of student academic performance; b) that at least one component in each typology predicts academic performance; and c) that student-teacher and student-student, evaluating students, and active interactions, respectively, have a significant impact on academic performance, while the other interaction types are not significantly related to academic performance

Learning Analytics and Interactions in Virtual Learning Environments. A Comparative Study of Typologies and their Relationship with Academic Performance

Analysis of learning data (learning analytics) is a new research field with high growth potential. The main objective of Learning analytics is the analysis of data (interactions being the basic data unit) generated in virtual learning environments, in order to maximize the outcomes of the learning process; however, a consensus has not been reached yet on which interactions must be measured and what is their influence on learning outcomes. This research is grounded on the study of e-learning interaction typologies and their relationship with students? academic performance, by means of a comparative study between different interaction typologies (based on the agents involved, frequency of use and participation mode). The main conclusions are a) that classifications based on agents offer a better explanation of academic performance; and b) that each of the three typologies are able to explain academic performance in terms of some of their components (student-teacher and student-student interactions, evaluating students interactions and active interactions, respectively), with the other components being nonrelevant

A new constitutive model for polymeric matrices: Application to biomedical materials

Semi crystalline polymeric composites are increasingly used as bearing material in the biomedical sector, mainly because of their specific mechanical properties and the new advances in 3D printing technologies that allows for customised devices. Among these applications, total or partial prostheses for surgical purposes must consider the influence of temperature and loading rate. This paper proposes a new constitutive model for semi-crystalline polymers, commonly used as matrix material in a wide variety of biomedical composites, that enables reliable predictions under a wide range of loading conditions. Most of the recent models present limitations to predict the non-linear behaviour of the polymer when it is exposed to large deformations at high strain rates. The proposed model takes into account characteristic behaviours of injected and 3D printed thermoplastic polymers such as material hardening due to strain rate sensitivity, thermal softening, thermal expansion and combines viscoelastic and viscoplastic responses. These viscous-behaviours are relevant for biomedical applications where temperature evolution is expected during the deformation process due to heat generation induced by inelastic dissipation, being essential the thermo-mechanical coupling consideration. The constitutive model is formulated for finite deformations within a thermodynamically consistent framework. Additionally, the model is implemented in a finite element code and its parameters are identified for two biomedical polymers: ultra-high-molecular-weight polyethylene (UHMWPE) and high density polyethylene (HDPE). Finally, the influence of viscous behaviours on dynamic deformation of semi-crystalline polymeric matrices is analysed

A continuum constitutive model for FDM 3D printed thermoplastics

Fused deposition modelling (FDM) is the most common additive manufacturing technology used for thermoplastic components. This layers-based manufacturing process results into direct links between printing parameters and the polymer mesostructure by means of porosity and structural anisotropy. These dependencies along with other features of thermoplastic polymers (i.e., nonlinearities, viscous and thermal responses) makes its constitutive modelling very challenging. This work distances from studies that model the 3D printing process. Instead, we aim at complementing such approaches with a continuum model to describe the macroscopic behaviour of FDM thermoplastics while preserving links with printing parameters. Prior to the modelling conceptualisation, experimental characterisation tests are conducted on ABS specimens to evaluate the influence of printing parameters on the macroscopic mechanical response. The physical fundamentals behind the deformation and failure mechanisms are identified and motivate the new constitutive model. This model is formulated for finite deformations within a thermodynamically consistent framework. The model accounts for: nonlinear response; anisotropic hyperelasticity related to a transversely isotropic distribution of porous; strain rate dependency; macroscopic stiffness dependent on 3D printing processing. Finally, the model is numerically implemented and calibrated for ABS with original experiments, demonstrating its suitability.The authors acknowledge support from Ministerio de Ciencia, Innovación y Universidades, Spain, Agencia Estatal de Investigación y Fondo Europeo de Desarrollo Regional, Spain, como entidades financiadoras (RTI2018-094318-B-I00). D.G.-G., S.G.-H. and A.A. acknowledge support from Programa de Apoyo a la Realización de Proyectos Interdisciplinares de I+D para Jóvenes Investigadores de la Universidad Carlos III de Madrid (BIOMASKIN-CM-UC3M). D.G.-G. acknowledges support from the Talent Attraction grant (CM 2018 - 2018-T2/IND- 9992) from the Comunidad de Madrid, Spain

Multi-impact mechanical behaviour of short fibre reinforced composites

High velocity transverse impact on reinforced composites is a matter of interest in the automotive, aeronautical and biomedical sectors. Most existing studies have addressed this problem by single isolated impacts; however, this work deals with the distinction between single, sequential and simultaneous impacts on composite structures. This paper proposes an experimental methodology to study the mechanical behaviour of materials under single and multi-impact loadings. The overall objective is to investigate the mechanical response of short carbon fibre reinforced PEEK when is subjected to single and multiple high velocity impacts. Experimental tests are conducted covering impact velocities from 90 m/s to 470 m/s. Energy absorption, damage extension and failure mechanisms are compared to assess additive and cumulative effects in high velocity impact scenarios. Experimental results show that the specific deformation and fracture mechanisms observed during multi-hitting events change with impact velocity. Compared to the behaviour of unreinforced thermoplastics, short fibre reinforced composites present significant limitations at velocities close to the ballistic limit, but multi-hit capability is observed at high impact velocity when the damage is mainly local. As key conclusion, the ballistic limit obtained in single impact test cannot be extrapolated to sequential and simultaneous tests. Multi-impact tests, especially close to the ballistic limit, are necessary to guarantee the structural integrity of composite structures in realistic impact scenarios.The researchers are indebted to Ministerio de Economía y Competitividad de España (Project DPI2014-57989-P) and Vicerrectorado de Política Científica UC3M (Project 2013-00219-002) for financial support

Modelado de la efectividad en el e-mail marketing – Una aproximación basada en la teoría de jerarquía de efectos

[EN] Despite the importance and pervasiveness of e-mail marketing, improving the effectiveness of e-mail marketing programs continues to be a priority for most businesses due to their revenue-generating potential. However, the study of e-mail marketing has been mostly neglected by academic research. More notably, the lack of holistic approaches and conceptual frameworks to tackle this challenge stand in the way of helping companies to better plan and deploy their e-mail marketing strategies and campaigns. This study addresses this issue by proposing a comprehensive model for the study of e-mail marketing effectiveness based on the hierarchy-of-effects theory. The effectiveness model is built by linking the stages of the AIDA (Attention, Interest, Desire, Action) model to the sequence of steps that consumers undergo when they interact with promotional e-mails. This approach allows identifying different partial effectiveness metrics associated with the cognitive, emotional and conative stages, which are later operationalized through key performance indicators with widespread adoption in the industry (open rate, clickthrough rate, retention rate and conversion rate). Thus, attention is linked to open effectiveness, interest is linked both to click effectiveness and subscriber retention effectiveness, and action is linked to conversion effectiveness. The stage of desire is dropped from the model because it usually takes place outside the e-mail marketing process. The study includes a practical illustration of the adequateness of the framework based on data and results from prior studies.[ES] Pese a la importancia y difusión del e-mail marketing, la mejora de su efectividad continúa siendo una prioridad para la mayoría de anunciantes dado su potencial para la generación de ingresos. Sin embargo, el estudio del e-mail marketing ha sido en gran parte ignorado por la comunidad científica. En concreto, la ausencia de enfoques holísticos y marcos conceptuales de estudio impiden a las compañías mejorar la planificación y ejecución de estrategias de e-mail marketing. Este estudio responde a este problema mediante la propuesta de un modelo general de efectividad de e-mail marketing basado en la teoría de jerarquía de efectos. Así, cada una de las fases del modelo AIDA (Atención, Interés, Deseo, Acción) se vincula a las diversas etapas del proceso secuencial experimentado por los consumidores en su interacción con los correos electrónicos promocionales. Esto permite identificar diferentes métricas parciales de efectividad asociadas a las etapas cognitiva, afectiva y conativa, que a su vez pueden ser operacionalizadas a través de tasas habitualmente utilizadas por la industria (apertura, clic, retención y conversión). En concreto, la etapa de atención queda vinculada a la efectividad de apertura, la etapa de interés a la efectividad de clic y de retención de suscriptores, y la etapa de acción a la efectividad de conversión. El modelo no asocia ninguna métrica a la etapa de deseo dado que ésta ocurre habitualmente fuera del proceso del e-mail marketing. El estudio incluye un ejemplo de la adecuación del modelo conceptual a partir de datos y resultados de estudios previos