Measuring collaborative emergent behavior in multi-agent reinforcement learning

Multi-agent reinforcement learning (RL) has important implications for the future of human-agent teaming. We show that improved performance with multi-agent RL is not a guarantee of the collaborative behavior thought to be important for solving multi-agent tasks. To address this, we present a novel approach for quantitatively assessing collaboration in continuous spatial tasks with multi-agent RL. Such a metric is useful for measuring collaboration between computational agents and may serve as a training signal for collaboration in future RL paradigms involving humans.Comment: 1st International Conference on Human Systems Engineering and Design, 6 pages, 2 figures, 1 tabl

Nutrient pollution of waters: eutrophication trends in European marine and coastal environments

En els darrers cinquanta anys, l'eutrofització (l'enriquiment natural o artificial de nutrients d'un ecosistema aquàtic) ha esdevingut un problema de contaminació ambiental àmpliament estès, a causa de l'augment de la població i de les àrees urbanes, així com de l'augment de producció en els sectors agrícoles i ramaders. Tot i que aquest problema és d'especial importància en els països desenvolupats i en zones d'elevada població, la implantació de sistemes d'agricultura intensiva en zones en desenvolupament (com els països de l'Est d'Europa), pot dur a la propagació de l'eutrofització en poques dècades. L'any 2004, per tal d'establir un nombre reduït d'indicadors estables, però que puguin mostrar tendències temporals i espacials, i que responguin a qüestions prioritàries de política ambiental, l'Agència Europea del Medi Ambient (EEA) va identificar un conjunt de 37 indicadors que cobreixen sis àrees ambientals i quatre sectors prioritaris respecte als quals es dirigeixen les estratègies de l'EEA. En aquest treball, l'avaluació de la informació facilitada per quatre indicadors seleccionats permet valorar la situació actual respecte a l'eutrofització als mars europeus. Es conclou que, tot i la creixent implantació de les directives europees dirigides a la millora de la qualitat del sistemes aquàtics, no s'ha observat en termes generals una reducció de l'eutrofització. Aquest fet emfatitza la lenta recuperació dels ecosistemes perjudicats per l'acció humana.In the last 50 years, eutrophication (the natural or artificial nutrient enrichment of an aquatic ecosystem) has become a widespread environmental pollution problem due to the growing population, rapid urbanization of previously rural areas, and increased agricultural and livestock production. Even though this problem has particular relevance in developed countries and in areas with large populations, the implementation of intensive agriculture systems in developing zones (such as in Eastern Europe) may lead to the further propagation of the eutrophication in the coming decades. In 2004, the European Environment Agency (EEA) set out to answer to certain priority policy questions. For this purpose, it selected a small number of relevant indicators that are stable but sensitive to temporal and spatial trends. The core set of 37 indicators (referred to as CSI) covers six environmental subjects and four sectors that reflect the priorities of the EEA. In this work, the information rendered by four of the 37 selected CSI was used to assess the current state of eutrophication in European seas. The analysis showed that, despite implementation of those EU Directives aimed at improving the quality of aquatic environments, no general reduction in eutrophication has occurred. This fact emphasizes the slow recovery rate of ecosystems damaged by human actions

Tools to support the self assessment of the performance of Food Safety Management Systems

Changes in food supply chains, health and demographic situations, lifestyle and social situations, environmental conditions, and increased legislative requirements have led to significant efforts in the development of quality and safety management systems in agribusiness and food industry worldwide (Ropkins and Beck, 2000; Efstratiadis, Karirti, and Arvanitoyannis, 2000; Jacxsens, et al, 2009a, Luning and Marcelis, 2009a). Nowadays, companies have implemented various quality assurance (QA) guidelines and standards, such as GMP and HACCP guidelines (like General Principles of food hygiene (Codex Alimentarius 2003), GFSI guidance document (GFSI (2007), and quality assurance standards (like ISO 9001:2008 (2008), ISO22000:2005 (2005), BRC (2008), and IFS (2007) into their company own food safety management system. The performance of such systems in practice is, however, still variable. Moreover, the continuous pressure on food safety management system (FSMS) performance and the dynamic environment wherein the systems operate (such as emerging pathogens, changing consumer demands, developments in preservation techniques) require that they can be systematically analysed to determine opportunities for improvement (Wallace, et al, 2005; Manning et al, 2006; Van der Spiegel et al, 2006; Cornier et al, 2007; Luning et al, 2009a). Within the European project entitled ‘PathogenCombat- EU FOOD-CT-2005-007081’ various tools have been developed to support food companies and establishments in systematically analysing and judging their food safety management system and its microbiological performance as basis for strategic choices on interventions to improve the FSMS performance. This chapter describes briefly principles of the major tools that have been developed and some others, which are still under still under construction

Fotografía DE DOS HOMBRES [Material gráfico]

RAMBLA DEL CENTRO 37. BARCELONACopia digital. Madrid : Ministerio de Educación, Cultura y Deporte, 201

Los criterios que inspiran los contratos modernos en el proyecto de Código Civil y Comercial de la Nación

Fil: Rovira, Alfredo L. Universidad de Buenos Aires. Facultad de Derecho. Cátedra Derecho Comercial. Buenos Aires, Argentin

Fitting in a complex chi^2 landscape using an optimized hypersurface sampling

Fitting a data set with a parametrized model can be seen geometrically as finding the global minimum of the chi^2 hypersurface, depending on a set of parameters {P_i}. This is usually done using the Levenberg-Marquardt algorithm. The main drawback of this algorithm is that despite of its fast convergence, it can get stuck if the parameters are not initialized close to the final solution. We propose a modification of the Metropolis algorithm introducing a parameter step tuning that optimizes the sampling of parameter space. The ability of the parameter tuning algorithm together with simulated annealing to find the global chi^2 hypersurface minimum, jumping across chi^2{P_i} barriers when necessary, is demonstrated with synthetic functions and with real data

Quorum-sensing regulates biofilm formation in Vibrio scophthalmi

Background: In a previous study, we demonstrated that Vibrio scophthalmi, the most abundant Vibrio species among the marine aerobic or facultatively anaerobic bacteria inhabiting the intestinal tract of healthy cultured turbot (Scophthalmus maximus), contains at least two quorum-sensing circuits involving two types of signal molecules (a 3-hydroxy-dodecanoyl-homoserine lactone and the universal autoinducer 2 encoded by luxS). The purpose of this study was to investigate the functions regulated by these quorum sensing circuits in this vibrio by constructing mutants for the genes involved in these circuits. Results. The presence of a homologue to the Vibrio harveyi luxR gene encoding a main transcriptional regulator, whose expression is modulated by quorumsensing signal molecules in other vibrios, was detected and sequenced. The V. scophthalmi LuxR protein displayed a maximum amino acid identity of 82% with SmcR, the LuxR homologue found in Vibrio vulnificus. luxR and luxS null mutants were constructed and their phenotype analysed. Both mutants displayed reduced biofilm formation in vitro as well as differences in membrane protein expression by mass-spectrometry analysis. Additionally, a recombinant strain of V. scophthalmi carrying the lactonase AiiA from Bacillus cereus, which causes hydrolysis of acyl homoserine lactones, was included in the study. Conclusions: V. scophthalmi shares two quorum sensing circuits, including the main transcriptional regulator luxR, with some pathogenic vibrios such as V. harveyi and V. anguillarum. However, contrary to these pathogenic vibrios no virulence factors (such as protease production) were found to be quorum sensing regulated in this bacterium. Noteworthy, biofilm formation was altered in luxS and luxR mutants. In these mutants a different expression profile of membrane proteins were observed with respect to the wild type strain suggesting that quorum sensing could play a role in the regulation of the adhesion mechanisms of this bacterium

La plataforma carbonatada epeírica (Formaciones Imón e Isábena) del Triásico superior del Noreste de la Península Ibérica

Las principales unidades litoestratigráficas localizadas en el límite Triásico/Jurásico del noreste de la Península Ibérica son las facies Keuper, los carbonatos de la Formación Imón/Formación Isábena y las dolomías, evaporitas y lutitas de la Formación Carniolas de Cortes de Tajuña/Zona de Anhidrita. Los carbonatos del Triásico superior son conocidos como Formación Imón en la Cordillera Ibérica, Cordilleras Costero Catalanas y Depresión del Ebro y como Formación Isábena en la vertiente surpirenaica. La asociación de foraminíferos (Gandinella falsofriedli, Aulotortus friedli, Trochammina jaunensis, Agathammina austroalpina, Trocholina cf. laevis y Trocholina crassa) localizada en la base de la Formación Imón y de la Formación Isábena determina una edad Alauniense terminal-Sevatiense medio (Noriense superior). La asociación de bivalvos (Neoschizodus reziae, Pseudocorbula alpina, Protocardia cf. Rhaetica y Laternula cf. amicii) localizada en la parte alta de la Formación Imón indica un “Retiense” (Noriense p.p.). La Formación Imón está constituida básicamente por dolomías bien estratificadas, mientras que la Formación Isábena está formada por calizas. La Formación Imón presenta dos tipos de dolomías: dolomías grises en la base y dolomías blancas a techo. A partir del estudio petrológico, mineralógico, de elementos traza e isótopos de oxígeno y de carbono de las dolomías, se ha establecido que las dolomías grises son de origen “seepage-reflux” y las dolomías blancas de origen hipersalino. Las curvas de isopacas de la Formación Imón son redondeadas a elongadas y presentan pendientes muy suaves, lo cual sugiere que la sedimentación de esta plataforma carbonatada estuvo controlada por la subsidencia termal. El modelo sedimentológico de los materiales carbonatados de la Formación Imón y de la Formación Isábena es el de una plataforma carbonatada epeírica.The lithostratigraphic units associated with the Triassic/Jurassic boundary in the northeast of the Iberian Peninsula are the Keuper evaporites and lutites, the Imón Formation/Isábena Formation carbonates and the Cortes de Tajuña Formation/Anhidrite zone evaporites, dolomitic breccias and lutites. The upper Triassic carbonates are known as the Imón Formation in the Iberian Ranges, the Catalan Coastal Ranges and the Ebro Depression, and as the Isábena Formation in the southern Pyrenees. The foraminifera associations (Gandinella falsofriedli, Aulotortus friedli, Trochammina jaunensis, Agathammina austroalpina, Trocholina cf. laevis and Trocholina crassa), which are located in the lower part of the Imón and Isábena sections, indicate a late Alaunian-mid Sevatian (late Norian) age. The bivalve associations (Neoschizodus reziae, Pseudocorbula alpina, Protocardia cf. rhaetica and Laternula cf. amicii), located in the uppermost part of the Imón Formation indicate a “Rhaetian” (Norian p.p.) age. The Imón Formation consists of stratified dolomites whereas the Isábena Formation is made up of limestones. The Imón dolomites present two dolomites types: grey dolsparites and white dolmicrites. These dolomites are interpreted as seepage-reflux (grey dolomites) and hypersaline dolomites (white dolomites) according to with their mineralogy, elemental geochemistry and stable isotope characteristics. The isopach curves are round to elongated with very gentle slopes, indicating that thermal subsidence played the main role in controlling the sedimentation of this upper Triassic carbonate platform. The sedimentary model of the Imón Formation and the Isábena Formation is an epeiric carbonate platform