Community structure in industrial SAT instances

Modern SAT solvers have experienced a remarkable progress on solving industrial instances. It is believed that most of these successful techniques exploit the underlying structure of industrial instances. Recently, there have been some attempts to analyze the structure of industrial SAT instances in terms of complex networks, with the aim of explaining the success of SAT solving techniques, and possibly improving them. In this paper, we study the community structure, or modularity, of industrial SAT instances. In a graph with clear community structure, or high modularity, we can find a partition of its nodes into communities such that most edges connect variables of the same community. Representing SAT instances as graphs, we show that most application benchmarks are characterized by a high modularity. On the contrary, random SAT instances are closer to the classical Erdös-Rényi random graph model, where no structure can be observed. We also analyze how this structure evolves by the effects of the execution of a CDCL SAT solver, and observe that new clauses learned by the solver during the search contribute to destroy the original structure of the formula. Motivated by this observation, we finally present an application that exploits the community structure to detect relevant learned clauses, and we show that detecting these clauses results in an improvement on the performance of the SAT solver. Empirically, we observe that this improves the performance of several SAT solvers on industrial SAT formulas, especially on satisfiable instances.Peer ReviewedPostprint (published version

Open Source Based Deployment of Environmental Data into Geospatial Information Infrastructures

Today, scientists use local and closed geospatial solutions to run their models and store their results. This may limit their ability to share their models, and results with other interested colleagues. This scenario is changing with the advent of new factors such as the rapid growth and rise of open source projects, or new paradigms promoted by government organizations to manage environmental data, such as Infrastructure for Spatial Information in the European Community (INSPIRE) directive, or the massive use of Web 2.0 techniques where users are looking for applications with a high degree of collaboration, interactiveness, and multimedia effects. Many authors address the versatility of Spatial Data Infrastructures where resources are shared and accessed via standard service according to complex specifications. In this context, the authors point out the need to merge the traditional building and maintenance of these infrastructures, driven by official providers, with these more participative methodologies where users can participate in creating and integrating information. It seems necessary to develop new geospatial tools which integrate these new trends. This paper proposes a unified solution offering to the scientific field an open development framework, based on standards and philosophies focused on new technologies and scientific needs

Predator Avoidance in the European Seabass After Recovery From Short-Term Hypoxia and Different CO2 Conditions

Short-term hypoxia that lasts just a few days or even hours is a major threat for the marine ecosystems. The single effect of the human-induced levels of hypoxia and other anthropogenic impacts such as elevated pCO2 can reduce the ability of preys to detect their predators across taxa. Moreover, both processes, hypoxia and elevated pCO2, are expected to co-occur in certain habitats, but the synergic consequences of both processes and the ability of fish to recover remain unknown. To provide empirical evidence to this synergy, we experimentally evaluated the risk-taking behavior in juveniles of the European seabass (Dicentrachus labrax), an important commercial fisheries species after recovering from short-term hypoxia and different pH scenarios. The behavior of seabass juveniles was monitored in an experimental arena before and after the exposure to a simulated predator and contrasted to control fish (BACI design) (current levels of hypoxia and elevated pCO2) using a mechanistic function-valued modeling trait approach. Results revealed that fish recovering from elevated pCO2, alone or combined with hypoxia, presented less avoidance behavior in failing to seek refuge when a simulated predator was present in the arena compared to those exposed to control pCO2 levels. Our results show that recovery from short-term exposure to acidification and hypoxia was not synergistic and suggest that recovery from acidification takes longer than from short-term hypoxia treatment through a potential effect on the sensorial and hence behavioral capacities of fish

Brachial artery peak velocity variation to predict fluid responsiveness in mechanically ventilated patients

Journal Article;ClinicalTrials.gov ID: NCT00890071INTRODUCTION Although several parameters have been proposed to predict the hemodynamic response to fluid expansion in critically ill patients, most of them are invasive or require the use of special monitoring devices. The aim of this study is to determine whether noninvasive evaluation of respiratory variation of brachial artery peak velocity flow measured using Doppler ultrasound could predict fluid responsiveness in mechanically ventilated patients. METHODS We conducted a prospective clinical research in a 17-bed multidisciplinary ICU and included 38 mechanically ventilated patients for whom fluid administration was planned due to the presence of acute circulatory failure. Volume expansion (VE) was performed with 500 mL of a synthetic colloid. Patients were classified as responders if stroke volume index (SVi) increased >or= 15% after VE. The respiratory variation in Vpeakbrach (DeltaVpeakbrach) was calculated as the difference between maximum and minimum values of Vpeakbrach over a single respiratory cycle, divided by the mean of the two values and expressed as a percentage. Radial arterial pressure variation (DeltaPPrad) and stroke volume variation measured using the FloTrac/Vigileo system (DeltaSVVigileo), were also calculated. RESULTS VE increased SVi by >or= 15% in 19 patients (responders). At baseline, DeltaVpeakbrach, DeltaPPrad and DeltaSVVigileo were significantly higher in responder than nonresponder patients [14 vs 8%; 18 vs. 5%; 13 vs 8%; P 10% predicted fluid responsiveness with a sensitivity of 74% and a specificity of 95%. A DeltaPPrad value >10% and a DeltaSVVigileo >11% predicted volume responsiveness with a sensitivity of 95% and 79%, and a specificity of 95% and 89%, respectively. CONCLUSIONS Respiratory variations in brachial artery peak velocity could be a feasible tool for the noninvasive assessment of fluid responsiveness in patients with mechanical ventilatory support and acute circulatory failure. TRIAL REGISTRATION ClinicalTrials.gov ID: NCT00890071.Ye

La dinámica de sistemas en la modelización de la influencia de la gestión del conocimiento en la industria agroalimentaria

En la actualidad las cadenas de suministro (CS) de la industria agroalimentaria (IAA) con sus particulares características, tienen el reto de incrementar sus niveles de productividad, calidad e innovación, a nivel global y local, para satisfacer los requerimientos alimenticios y nutricionales de la población. Según Davenport y Prusak (2000), en el siglo XXI la competitividad y la sostenibilidad de las organizaciones productivas, se basa en los activos del conocimiento y su gestión. La gestión de los activos intangibles es clave para la creación de valor en las organizaciones y fuente de ventaja competitiva. En tal sentido, la gestión del conocimiento (GC) representa una herramienta que permite mejorar el rendimiento y el desempeño de las cadenas de suministro de productos agroalimentarios (Sporleder, 2005). Aunque son muchas y variadas las definiciones de GC, debido a que es un concepto inmaduro, en esta investigación la GC se define como una estrategia organizacional que basada en un ambiente innovador y en el uso de las TIC, desarrolla capacidades para: originar, almacenar, transferir, aplicar y proteger el conocimiento organizacional, con la finalidad de incrementar la competitividad y sustentabilidad de las CS y las organizaciones o empresas que las conforman (Martínez, 2011)

Ocean acidification increases fatty acids levels of larval fish

Rising levels of anthropogenic carbon dioxide in the atmosphere are acidifying the oceans and producing diverse and important effects on marine ecosystems, including the production of fatty acids (FAs) by primary producers and their transfer through food webs. FAs, particularly essential FAs, are necessary for normal structure and function in animals and influence composition and trophic structure of marine food webs. To test the effect of ocean acidification (OA) on the FA composition of fish, we conducted a replicated experiment in which larvae of the marine fish red drum (Sciaenops ocellatus) were reared under a climate change scenario of elevated CO levels (2100 matm) and under current control levels (400 matm). We found significantly higher whole-body levels of FAs, including nine of the 11 essential FAs, and altered relative proportions of FAs in the larvae reared under higher levels of CO. Consequences of this effect of OA could include alterations in performance and survival of fish larvae and transfer of FAs through food webs.CDG was funded by FPI‐INIA-2012, this manuscript was financed by the research project REC2  (grant#CTM2011‐23835). Contribution 1705 of the University of Texas Marine Science InstitutePeer Reviewe

Inventario de fenómenos gravitacionales en el Occidente de Cuba

The present paper has as objective to elaborate an inventory of gravitational phenomenon’s in the most western area in Cuba that offers a more integral vision of the susceptibility from the territory to the occurrence of this phenomenon. For it, they were carried out two inventories of gravitational phenomenon’s, one associated to the road through a field work and the other based in the photograph interpretation of satelital images obtained by the googgle earth.  As a result, an inventory was obtained where they register the slides of the area and its more particular characteristics are described, elements that were not shown in an integral way until the moment, what facilitates, to interpret the results better and to determine the variables that exercise bigger influence in the occurrence of these phenomenon’s, is also shown, the most susceptible sectors to the occurrence of these. For better to graph the results three maps are elaborated, two that show the density of phenomenon’s for Popular Council and the third associate the populational density with the areas where they register the slides.El presente artículo tiene como objetivo elaborar un inventario de deslizamientos en la zona más occidental de Cuba, que brinde una visión más integral de la susceptibilidad del territorio a la ocurrencia de dichos fenómenos gravitacionales. Para ello, se realizaron dos inventarios de fenómenos gravitacionales, uno asociado a las redes viales a través de trabajos de campo y el otro a partir de la fotointerpretación de imágenes satelitales obtenidas del Googgle Earth. Como resultado, se obtuvo un inventario donde se registran los deslizamientos de la zona y se describen sus características más particulares, elementos que hasta el momento no se mostraban de manera integral, lo que posibilita, interpretar mejor los resultados y determinar las variables que ejercen mayor influencia en la ocurrencia de estos fenómenos, se muestra además, los sectores más susceptibles a la ocurrencia de estos. Para graficar mejor los resultados se elaboran tres mapas, dos que muestran la densidad de fenómenos por Consejos Populares y el tercero asocia la densidad poblacional con las zonas donde se registran los deslizamientos. Como conclusión fundamental y a partir de los resultados de la investigación se pudo constatar que los inventarios de deslizamientos representan una herramienta útil como punto de partida para el estudio de riesgo y susceptibilidad de un territorio

Inventory of gravitational phenomena in the West of Cuba

The present paper has as objective to elaborate an inventory of gravitational phenomenon’s in the most western area in Cuba that offers a more integral vision of the susceptibility from the territory to the occurrence of this phenomenon. For it, they were carried out two inventories of gravitational phenomenon’s, one associated to the road through a field work and the other based in the photograph interpretation of satelital images obtained by the google earth. As a result, an inventory was obtained where they register the slides of the area and its more particular characteristics are described, elements that were not shown in an integral way until the moment, what facilitates, to interpret the results better and to determine the variables that exercise bigger influence in the occurrence of these phenomenon’s, is also shown, the most susceptible sectors to the occurrence of these. For better to graph the results three maps are elaborated, two that show the density of phenomenon’s for Popular Council and the third associate the populational density with the areas where they register the slides

Spatio-temporal composition and dynamics of zooplankton in the Kalmar Sound (western Baltic Sea) in 2009-2010

In pelagic food webs, zooplankton is the link between lower and higher trophic levels. It is thus essential to know how the zooplankton community structure varies with its environment. We investigated the seasonal and spatial variation in the zooplankton diversity and community structure during two consecutive years in the Kalmar Sound, along the Swedish east coast, an area with a strong bathymetric gradient and of high ecological importance for e.g. commercial fish species. Two zooplankton communities were identified in the area: a coastal/estuarine community in the south and an open-water community in the north. They were separated mainly by differing salinity and temperature conditions. Biodiversity increased from spring to autumn and was higher in the open waters. © 2014.C. Díaz-Gil, M. Werner, O. Lövgren, O. Kaljuste and M. Casini were partially funded by the Swedish PLAN FISH project, financed by the Swedish Environmental Protection Agency and the Swedish Agency for Marine and Water Management. C. Díaz-Gil was also funded by the EU Erasmus Program for international mobility of studentsPeer Reviewe

Estudio de técnicas de planificación dinámica de planes de ocio

Este proyecto, 'Olétrip', es la continuación de una versión anterior cuyos autores fueron Raquel Álvarez Hernández, Qiang Sun y YanYan Cheng. Nuestro objetivo en el proyecto es mejorar las recomendaciones de un sistema de planes de ocio usando diferentes algoritmos para calcular las rutas más óptimas con la ayuda de un validador personalizado. Los algoritmos nuevos implementados en la aplicación son los siguientes: • Algoritmo aleatorio: se implementó para ayudarnos a familiarizarnos con el código heredado del proyecto anterior, y posteriormente resultó útil para la implementación del algoritmo genético. • Algoritmo de primero el mejor (BFS): se usa para la búsqueda de la ruta más corta después de que el usuario haya especificado todos los detalles del viaje. • Algoritmo genético: este algoritmo se realizó con la idea de construir un plan óptimo, a pesar de saber que requiere de bastante tiempo y consumo de recursos... pero finalmente se optó por ese algoritmo para los viajeros que saben a qué ciudad quieren ir pero que no saben qué visitar. Se explicará las ventajas y desventajas que nos supone optar por un algoritmo u otro, el cómo se ha implementado cada uno de ellos y los cambios que han sido necesarios abordar con respecto a la anterior versión del proyecto. Incorporaremos a Olétrip un validador de planes que se encargará en la parte del backend de considerar la eficiencia que tiene un plan partiendo de unos requisitos que hemos definido. Será de gran importancia esta nueva funcionalidad de validación ya que los algoritmos implementados manejan una cantidad importante de planes y de esta manera nos ayuda a evaluar qué planes son más eficientes. La interfaz utilizada será la misma que en su anterior versión, incorporando una interfaz nueva que sirve para el recomendar de planes a los usuarios indecisos. También hemos incorporado un simulador de planes para los usuarios Admin que ayuda a la hora de implementar alguna funcionalidad nueva en la aplicación. De esta manera realizaremos una serie de evaluaciones con el usuario realizando un estudio de los distintos algoritmos, analizando así los resultados obtenidos y la satisfacción del usuario