Coherence-length effects in fast atom diffraction at grazing incidence

Coherence properties of projectiles, found relevant in ion-atom collisions, are investigated by analyzing the influence of the degree of coherence of the atomic beam on interference patterns produced by grazing-incidence fast-atom diffraction (GIFAD or FAD). The transverse coherence length of the projectiles, which depends on the incidence conditions and the collimating setup, determines the overall characteristics of GIFAD distributions. We show that for atoms scattered from a LiF(001) surface after a given collimation, we can modify the interference signatures of the angular spectra by varying the total impact energy, while keeping the normal energy as a constant. Also, the role played by the geometry of the collimating aperture is analyzed, comparing results for square and circular openings. Furthermore, we study the spot-beam effect, which is due to different focus points of the impinging particles. We show that when a region narrower than a single crystallographic channel is coherently illuminated by the atomic beam, the spot-beam contribution strongly affects the visibility of the interference structures, contributing to the gradual quantum-classical transition of the projectile distributions.Fil: Gravielle, Maria Silvia. Consejo Nacional de Investigaciónes Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Astronomía y Física del Espacio. - Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Astronomía y Física del Espacio; ArgentinaFil: Miraglia, Jorge Esteban. Consejo Nacional de Investigaciónes Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Astronomía y Física del Espacio. - Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Astronomía y Física del Espacio; ArgentinaFil: Frisco, Leandro. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentin

Les médias sociaux d’entreprise pour favoriser la maturité numérique

Abstract: Developing their digital maturity is one of the most important goals of contemporary organizations. However, succeeding in this endeavor requires constant changes in the fabric of organizations and within their value-creation processes. Previous studies provided evidence of the benefits of enterprise social media to support value-creation shifts. Hence, exploring the use of enterprise social media to support digital maturity development seems coherent, although underexplored in the extant literature, especially in the context of small organizations. This doctoral research addresses this gap, by studying the use of enterprise social media, an affordable and intuitive technology, to support the development of digital maturity in the context of a small organization. To accomplish this task, we embraced an action research methodology for context understanding and problem-solving. Several data collection techniques were applied, and a template analysis approach supported data analyses, guiding the development of the action research cycles. Our research proposes a theoretical framework in which enterprise social media is likely to trigger different value-creation shifts within the partner organization, supporting the development of a flexible structure to face the challenges of the turbulent digital business environment. The proposed framework is drawn on emergent insights from the action research interventions applied in the context of a small organization. Results suggest that the different forms of value-creation related to the use of enterprise social media platforms supported the partner organization to develop its digital maturity, contributing to the Sociotechnical Systems perspective and the Contingency Theory. Moreover, while describing that technology implementation alone will not advance an organization’s digital maturity, this paper provides managers with insights into how to use enterprise social media as part of their digital maturity strategies, to assess their organizations’ enterprise social media maturity level, and to understand the potential of enterprise social media to create value in the digital business environment.Développer leur maturité numérique est l'un des objectifs les plus importants des entreprises contemporaines. La réussite de cet objectif nécessite des changements constants dans le tissu des organisations et dans leurs processus de création de valeur. Des études antérieures ont démontré les avantages des médias sociaux d'entreprise pour soutenir le changement dans la création de valeur des organisations. Par conséquent, étudier l'utilisation des médias sociaux d'entreprise pour soutenir le développement de la maturité numérique semble cohérent, bien que sous-exploré dans la littérature existante. Pour élargir les connaissances à ce sujet, la présente recherche doctorale vise à comprendre l'utilisation des médias sociaux d'entreprise, une technologie abordable et intuitive pour soutenir le développement de la maturité numérique, dans le cadre d'une petite organisation. La recherche a été menée en s'appuyant sur une méthodologie de recherche-action, afin de bien comprendre le contexte et de soutenir l’organisation partenaire dans ces objectives. Plusieurs techniques de collecte de données ont été employées, et une approche de template analysis a soutenu les analyses de données, guidant le développement des cycles de recherche-action. Notre recherche propose un modèle théorique qui explore l'influence des médias sociaux d'entreprise sur la création de valeur au sein d'une petite organisation. Le cadre théorique proposé a été appliqué dans le contexte de l'organisation partenaire, ce qui nous a permis de constater que les différentes formes de création de valeur liées à l'utilisation des plateformes de médias sociaux d'entreprise ont aidé l'organisation partenaire à développer sa maturité numérique, en ajoutant des contributions aux théories sociotechniques et des contingences. Des contributions managériales de cette recherche incluent des consignes détaillées sur la façon d'utiliser les médias sociaux d'entreprise dans le cadre de leurs stratégies numériques, d'évaluer le niveau de maturité des médias sociaux d'entreprise de leur organisation et de comprendre le potentiel des médias sociaux d'entreprise pour créer de la valeur dans l'environnement numérique d'affaires

Reseñas

VV.AA. Networks & Matters : a blog on Actor-Network Theory and philosophical empiris

Full evolution of low-mass white dwarfs with helium and oxygen cores

We study the full evolution of low-mass white dwarfs with helium and oxygen cores. We revisit the age dichotomy observed in many white dwarf companions to millisecond pulsar on the basis of white dwarf configurations derived from binary evolution computations. We evolve 11 dwarf sequences for helium cores with final masses of 0.1604, 0.1869, 0.2026, 0.2495, 0.3056, 0.3333, 0.3515, 0.3844, 0.3986, 0.4160 and 0.4481 M. In addition, we compute the evolution of five sequences for oxygen cores with final masses of 0.3515, 0.3844, 0.3986, 0.4160 and 0.4481 M. A metallicity of Z = 0.02 is assumed. Gravitational settling, chemical and thermal diffusion are accounted for during the white dwarf regime. Our study reinforces the result that diffusion processes are a key ingredient in explaining the observed age and envelope dichotomy in low-mass helium-core white dwarfs, a conclusion we arrived at earlier on the basis of a simplified treatment for the binary evolution of progenitor stars. We determine the mass threshold where the age dichotomy occurs. For the oxygen white dwarf sequences, we report the occurrence of diffusion-induced, hydrogen-shell flashes, which, as in the case of their helium counterparts, strongly influence the late stages of white dwarf cooling. Finally, we presensent our results as a set of white dwarf mass–radius relations for helium and oxygen cores.Fil: Panei, Jorge Alejandro. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Astrofísica La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas. Instituto de Astrofísica La Plata; ArgentinaFil: Althaus, Leandro Gabriel. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Astrofísica La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas. Instituto de Astrofísica La Plata; ArgentinaFil: Chen, X.. Chinese Academy of Sciences; República de ChinaFil: Han, Z.. Chinese Academy of Sciences; República de Chin

Strategic plan for a born global firm and the contribution of network relationships in the process of internationalization: Attentive

The present Master thesis is introduced upon the form of a Strategic Plan, which is intended to express the commercial viability of the internationalization of a born global firm in the United States. Therefore, Attentive is a startup that has the ambition to make a relevant impact in the Software-as-a-Service applications for business to business market. In order to achieve the main objective of this dissertation, it is carried out the internal analysis of the company, external and competitive market. As well as a secondary source for the accomplishment of this same dissertation was used the literature review, based on different approaches regarding networking relationships, the advantages and challenges of born globals to compete with mature companies in foreign markets in a deductive and inductive perspective have been developed by different authors. In terms of the functional presentation of the Strategic plan, during this thesis it will be explored the characterization of the sector, the choice of the new physical location and the establishment of the marketing mix components. Furthermore and to conclude this dissertation, the final chapter is going to be an evaluation of the impact of strategic control and Scoreboard card to make this plan the most complete possible

Utilisation d'un modèle réduit expérimental comme référence pour la validation des modèles d'inondations en zone urbaine

Recent advances in flood modelling of urban areas have lead to the development of more sophisticated urban flood models. These models simulate flooding events by coupling the surface flow and the sewer system with an internal boundary condition (IBC). However, good quality data of flood events are hazardous to obtain. In this work we aim to present quality data (i.e. discharges and water levels at several locations) collected from an experimental scaled-model for enabling a benchmark test for urban flood models. In addition the IBC discharge coefficients provided herein are determined experimentally enabling a consistent validation of drainage models. The scaled model comprises of a rectangular surface-channel with a downstream weir discharge, and with six inlets with identical diameter. The experimental results indicate: (1) consistency between the discharges measured by the ADV/WRP and the volumetric method (2) consistency of the water levels obtained in each WRPs; (2) Good correlation between the inlet discharge coefficients, and the weir discharge coefficient (3) The centre inlets show a higher discharge than the side inlets and the downstream inlets show a higher discharge than the upstream ones.L’évolution actuelle de la modélisation des inondations urbaines a conduit au développement d´améliorations importantes des modèles d'inondations en milieu urbain. Ces modèles de programmation mathématique simulent des inondations en tenant compte de l'interaction entre l'écoulement de surface et l'écoulement dans le réseau d'assainissement. Toutefois, il est difficile d'obtenir des données de qualité sur ces inondations. Ce travail vise à présenter des données de qualité mesurées à l'échelle expérimentale (déversements et niveaux d’eau en divers points d'un canal), pour être utilisé comme test de référence et donc comme benchmark pour la validation des modèles d’inondations urbaines. De plus, les coefficients de déversement présentés sont calculés expérimentalement, permettant ainsi la validation des modèles d'assainissement. Le modèle à l'échelle est un canal rectangulaire avec renvoi du déversoir en aval et six arrivées de diamètre identique. Les résultats de l'expérience indiquent: (1) la cohérence entre les déversements mesurés par les sondes ADV/WRP et les résultats de la méthode volumétrique; (2) la cohérence des niveaux d'eau obtenus pour chaque sonde WRP; (3) une bonne corrélation entre le coefficient de déversement d’arrivée et le coefficient de déversement du déversoir en aval; (4) les arrivées au centre présentent des coefficients de déversement plus grands, de même que les arrivées en aval

Analytical and numerical solutions of the Local Inertial Equations

This is the author accepted manuscript. The final version is available from Elsevier via the DOI in this record.Neglecting the convective terms in the Saint-Venant Equations (SVE) in flood hydrodynamic modelling can be done without a loss in accuracy of the simulation results. In this case the Local Inertial Equations (LInE) are obtained. Herein we present two analytical solutions for the Local Inertial Equations. The first is the classical instantaneous Dam-Break Problem and the second a steady state solution over a bump. These solutions are compared with two numerical schemes, namely the first order Roe scheme and the second order MacCormack scheme. Comparison between analytical and numerical results shows that the numerical schemes and the analytical solution converge to a unique solution. Furthermore, by neglecting the convective terms the original numerical schemes remain stable without the need for adding entropy correction, artificial viscosity or special initial conditions, as in the case of the full SVE.This research is partially funded by the FCT (Portuguese Foundation for Science and Technology) through the Doctoral Grant SFRH/BD/81869/2011 financed through the POPH/FSE program (Programa Operacional Potencial Humano/Fundo Social Europeu). This study had the support of the Portuguese Foundation for Science and Technology (FCT) Project UID/MAR/04292/2013