Hierarchy and Competition in CSCW applications: Model and case study

CSCW applications need to adapt themselves to the functional and organizational structures of people that use them. However they do not usually support division in groups with a certain hierarchical structure among them. In this paper, we propose and study a theoretical model of groupware appliations that reflects those hierarchical interactions. The proposed model is also intended to evaluate the effects in performance derived from competitive and collaborative relationships among the components of a hierarchy of groups. In order to demonstrate the above ideas, a groupware game, called Alymod, was designed and implemented using a modified version of a well-known CSCW Toolkit, namely Groupkit. Groupkit was modified in order to support group interactions in the same CSCW application. In Alymod, participants compete or collaborate within a hierarchical structure to achieve a common goal (completing gaps in a text, finishing numerical series, resolving University course examinations, etc.).Publicad

Directional vortex motion guided by artificially induced mesoscopic potentials

Rectangular pinning arrays of Ni dots define a potential landscape for vortex motion in Nb films. Magnetotransport experiments in which two in-plane orthogonal electrical currents are injected simultaneously allow selecting the direction and magnitude of the Lorentz force on the vortex-lattice, thus providing the angular dependence of the vortex motion. The background dissipation depends on angle at low magnetic fields, which is progressively smeared out with increasing field. The periodic potential locks in the vortex motion along channeling directions. Because of this, vortex-lattice direction of motion is up to 85o away from the applied Lorentz force direction.Comment: PDF file includes figure

Temperature dependence and mechanisms for vortex pinning by periodic arrays of Ni dots in Nb films

Pinning interactions between superconducting vortices in Nb and magnetic Ni dots were studied as a function of current and temperature to clarify the nature of pinning mechanisms. A strong current dependence is found for a square array of dots, with a temperature dependent optimum current for the observation of periodic pinning, that decreases with temperature as (1-T/Tc)3/2. This same temperature dependence is found for the critical current at the first matching field with a rectangular array of dots. The analysis of these results allows to narrow the possible pinning mechanisms to a combination of two: the interaction between the vortex and the magnetic moment of the dot and the proximity effect. Moreover, for the rectangular dot array, the temperature dependence of the crossover between the low field regime with a rectangular vortex lattice to the high field regime with a square configuration has been studied. It is found that the crossover field increases with decreasing temperature. This dependence indicates a change in the balance between elastic and pinning energies, associated with dynamical effects of the vortex lattice in the high field range.Comment: 12 text pages (revtex), 6 figures (1st jpeg, 2nd-6th postscript) accepted in Physical Review

New high resolution calcareous nannofossil analysis across the Danian / Selandian transition at the Zumaia section: comparison with South Tethys and Danish sections

A high resolution calcareous nannofossil biostratigraphic analysis was carried out across the Danian/Selandian transition at the Zumaia section (western Pyrenees). In the studied interval, spanning Varol’s Subzone NTp7a to Zone NTp9, a sequence of 10 distinct calcareous nannofossil events is identified. The recognition of these bioevents confirms the continuous and expanded character of the Zumaia section and allows an accurate biostratigraphic correlation of the D/S transition between Zumaia, the Danish reference sections and the more southerly Tethys sections. According to this correlation, the abrupt transition from the upper Danian limestones (the calcisiltite unit) to the Lellinge Greensand that marks the D/S boundary in the type area correlates with the lithological change from the Aitzgorri Limestone Formation to the Itzurun Formation in Zumaia. The calcareous nannofossil bioevents recorded in connection with the organic-rich layer used to mark the base of the Selandian in the Tethys region were detected in Zumaia ~10 m below the top of the Aitzgorri Limestone Formation. This finding suggests that the organic-rich layer is considerably older than the Danian/Selandian (D/S) boundary at Zumaia and the type area, and thus using it to mark the D/S boundary in Tethys is not appropriate. According to a counting of limestone/marl couplets, which are demonstrated to be the stratigraphic expression of precession cycles throughout the Zumaia section, the organic-rich layer in the Tethys region is ~546 kyr older than the D/S boundary at the type area

Delta invariant of curves on rational surfaces I. An analytic approach

We prove that if (C, 0) is a reduced curve germ on a rational surface singularity (X, 0) then its delta invariant can be recovered by a concrete expression associated with the embedded topological type of the pair C X. Furthermore, we also identify it with another (a priori) embedded analytic invariant, which is motivated by the theory of adjoint ideals. Finally, we connect our formulae with the local correction term at singular points of the global Riemann-Roch formula, valid for projective normal surfaces, introduced by Blache

Projecting more sustainable product and service designs

Product and service development based on sustainable criteria is one of the poles of innovation in design activity. Public policies, consumer preferences, and corporate social responsibility lead to the growing importance of applying sustainability principles in the current design process. However, to make this practice widespread, sustainability assessment must be included in the curricula of bachelor’s and master’s degrees in design, so that the graduates have the precise tools to use when they start their professional careers. Furthermore, sustainable design methods have mainly been applied to improve only the environmental behavior of products. In this work, a methodology that simultaneously evaluates environmental, economic, and social aspects was applied to project more sustainable designs of products and services. This approach was implemented in higher education to develop Bachelor’s and Master’s degree final projects by design engineering students. Collaboration with different companies and institutions allowed the study of a number of cases. The production process of a cash management machine, the service provided by a public nursery school, and the development of an itinerary exhibition were addressed. In each case, product and service requirements were analyzed, sustainability indicators were obtained, and more sustainable designs could be proposed. This experience is also part of a global strategy at the University of Zaragoza to support the implementation of the UN’s Sustainable Development Goals, enhancing sustainability education. The intention of this paper is to present a methodology for more sustainable design, and examples of its application that other teachers can easily follow when teaching design of products or services. © 2021 by the authors. Licensee MDPI, Basel, Switzerland

Influence of Polarity and Activation Energy in Microwave-Assisted Organic Synthesis (MAOS)

The aim of this work was to determine the parameters that have decisive roles in microwave-assisted reactions and to develop a model, using computational chemistry, to predict a priori the type of reactions that can be improved under microwaves. For this purpose, a computational study was carried out on a variety of reactions, which have been reported to be improved under microwave irradiation. This comprises six types of reactions. The outcomes obtained in this study indicate that the most influential parameters are activation energy, enthalpy, and the polarity of all the species that participate. In addition to this, in most cases, slower reacting systems observe a much greater improvement under microwave irradiation. Furthermore, for these reactions, the presence of a polar component in the reaction (solvent, reagent, susceptor, etc.) is necessary for strong coupling with the electromagnetic radiation. We also quantified that an activation energy of 20-30 kcal mol-1 and a polarity (µ) between 7-20 D of the species involved in the process is required to obtain significant improvements under microwave irradiation

Análisis del funcionamiento de una red colectiva ante distintas estrategias de riego en parcela

En zonas colectivas de riego, la tarifa a pagar por los agricultores está muy condicionada con el gasto energético de los equipos de bombeo, relacionada a su vez con la cantidad de agua aplicada a los cultivos. Así pues, es necesario el desarrollo de herramientas de ayuda a la toma de decisiones que busquen mejorar la eficiencia en el uso del agua y la energía, sin comprometer el rendimiento y productividad de los cultivos. El objetivo del trabajo es analizar el consumo energético en una estación de bombeo de una red colectiva de riego a la demanda ante distintos escenarios de riego en parcela y de presiones en la cabecera. La metodología propuesta ha sido aplicada a la zona regable de Tarazona de La Mancha (Albacete, España). Se han establecidos dos manejos de riego en parcela (con y sin déficit) para los principales cultivos de la zona y diferentes estrategias de presiones en la cabecera (variable y fija), para analizar el efecto sobre la eficiencia y consumo energético del bombeo. Para ello, se ha utilizado una herramienta de simulación desarrollada en MATLAB®, en combinación con el motor de cálculo EPANET®, y se ha aplicado como ejemplo a un día de elevada demanda de agua en la red. Los resultados indican que la utilización de presión en cabecera variable y manejo deficitario, genera ahorros energéticos de 12,43% en relación al mismo manejo con presión fija

Sustainability in the design of an itinerant cultural exhibition. Study of two alternatives

The sustainability improvement of museums and exhibitions is a recent concern for multiple organisations. The application of sustainability criteria is one of the most important strategies of innovation in design activities, products, and service systems. This study analyses the sustainability of two alternatives to an itinerant cultural exhibition service. The exhibition travels to 12 destinations over 3 years and is within a space of 300 m2. In the first alternative, the contents are printed and exposed on a physical medium, and in the second, audiovisual media projects the contents on the walls. Life cycle sustainability assessment is applied to evaluate the impacts in the environmental dimension and the economic and social dimensions. The calculation of indicators, such as the greenhouse gas emissions, total costs, and working time, which are referred to each sustainability dimension, is conducted. A descriptive, comparative study was performed to identify the impact factors with a higher incidence. The results demonstrate that the audiovisual exhibition is more sustainable than the printed exhibition, with a difference of 8.7%, 7%, and 6.6% in GWP100, CE, and TW indicators, respectively. © 2021 by the authors. Licensee MDPI, Basel, Switzerland

Commensurate and Incommensurate Vortex Lattice Melting in Periodic Pinning Arrays

We examine the melting of commensurate and incommensurate vortex lattices interacting with square pinning arrays through the use of numerical simulations. For weak pinning strength in the commensurate case we observe an order-order transition from a commensurate square vortex lattice to a triangular floating solid phase as a function of temperature. This floating solid phase melts into a liquid at still higher temperature. For strong pinning there is only a single transition from the square pinned lattice to the liquid state. For strong pinning in the incommensurate case, we observe a multi-stage melting in which the interstitial vortices become mobile first, followed by the melting of the entire lattice, consistent with recent imaging experiments. The initial motion of vortices in the incommensurate phase occurs by an exchange process of interstitial vortices with vortices located at the pinning sites. We have also examined the vortex melting behavior for higher matching fields and find that a coexistence of a commensurate pinned vortex lattice with an interstitial vortex liquid occurs while at higher temperatures the entire vortex lattice melts. For triangular arrays at incommensurate fields higher than the first matching field we observe that the initial vortex motion can occur through a novel correlated ring excitation where a number of vortices can rotate around a pinned vortex. We also discuss the relevance of our results to recent experiments of colloidal particles interacting with periodic trap arrays.Comment: 8 figure