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

Analysis of soil carbon in Spanish agricultural soils: relevant aspects in relation to the organic farming reconversion in the Mediterranean area

Los niveles de carbono orgánico en suelos agrícolas son especialmente relevantes en los modelos de gestión que se basan en la reserva orgánica de nutrientes. La disminución de materia orgánica que ocurre en los suelos roturados puede en algunos casos determinar la degradación del suelo. Este hecho puede ser especialmente relevante en condiciones climáticas límite (secas y semiáridas). A partir del análisis de una base de datos de suelos españoles se discute la distribución del C en el horizonte superficial de suelo según el clima y según el uso. Para cada área climática, mediante comparación entre suelos forestales y agrícolas se observa que los suelos de clima semiárido presentan una mayor resistencia a la pérdida de C y una menor resiliencia que los suelos de climas más húmedos. Este hecho nos hace pensar que los suelos semiáridos pueden estar cerca de los umbrales de degradación y que por lo tanto su gestión debería evitar les pérdidas de materia orgánica.Organic carbon levels in agricultural soils are specially relevant in the management models based on the organic reserve of the soil. Losses of soil organic matter that occur associated to tillage practices can enhance, in some cases, soil degradation. This fact may be specially relevant in dry and semiarid climates. By analysing a soil data base of the Spanish forest and agricultural soils we discuss the distribution of C in the soil surface horizon across climates and land uses. In each climatic area, by comparing forest with agricultural soils we found that soils in semiarid climate show greater resistance to soil C losses and lower resilience than soils of wetter climates. This fact suggest that semiarid soils can be at or near soil degradation thresholds and thus its management should avoid any losses of soil organic matter.Este trabajo ha sido posible gracias a un convenio establecido entre la Dirección General de Evaluación Ambiental del Ministerio de Medio Ambiente y la Universidad de Barcelona

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

First report of Erysiphe corylacearum causing powdery mildew on Corylus avellana in Spain

In the Mediterranean basin area, powdery mildew disease on hazelnut is commonly caused by Phyllactinia guttata. The disease occurs in late summer-autumn causing limited damage or economic impact. In April 2021, an unusual outbreak of the disease was observed on lower leaves of hazelnuts (cvs, Negret and San Giovanni) leading to rapid leaf desiccation in two commercial orchards (Camí de la Serra and Mas de la Coma), both located at La Selva del Camp, Tarragona, in north-eastern Spain. Unlike P. guttata, roundish spots of white mycelium appeared on the adaxial side of the leaves (Figure 1). Fruit was also infected and damaged.info:eu-repo/semantics/publishedVersio

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

Fundamentos científicos de la rehabilitación tras la sustitución intraarticular del ligamento cruzado anterior

Hay pocos aspectos de la rehabilitación en nuestra especialidad que sean tan complejos y controvertidos como la rehabilitación después de la sustitución intraarticular del ligamento cruzado anterior (LCA). La tendencia actual es utilizar protocolos de rehabilitación acelerada y rápido funcionalismo, todo lo cual está en relación directa con el avance en la investigación sobre el comportamiento biológico de los implantes, una mayor sofisticación en la técnica quirúrgica y los adelantos en las técnicas de rehabilitación. El objetivo de este trabajo es analizar no protocolos concretos, sino los problemas que plantea la cirugía del LCA y como minimizarlos en la medida de lo posible, protegiendo al mismo tiempo la plastia.There are few aspects of rehabilitation in our speciality which are so complex and controversial like rehabilitation after intraarticular replacement of the anterior cruciate ligament (ACL). Nowadays there is a trend to use protocols of accelerated rehabilitation and rapid functioning, and all this is related to the advances in research on the biological behavior of the grafts, a major sophistication in surgical technique and advances in rehabilitation techniques. The objective of this paper is not to analyze concrete protocols but rather the problems that state the surgery of the ACL, and how to diminish them to maximum, protecting at the same time the graft

Análise de Transiçao Resistiva e da irreversibilidade magnètica no superconductor YBACUO texturizado

Os supercondutores de alta temperatura crítica, em especial os granulares, apresentam uma transição resistiva que ocorre em duas etapas: a uma temperatura acima da temperatura crítica de transição Tc0, chamada de supercondutividade intragranular e a uma temperatura mais baixa onde ocorre a supercondutividade em toda a amostra, chamada de supercondutividade intergranular. Em Tc0 ocorre à ativação das ligações fracas e uma ordem de longo alcance é obtida, neste momento, a resistência elétrica é nula em toda amostra. Nos supercondutores de alta temperatura crítica, a linha de irreversibilidade magnética divide o estado misto do plano H-T em duas regiões: reversível e irreversível. Na região reversível todo o transporte elétrico sofre dissipação devido aos efeitos da dinâmica de fluxo magnético no supercondutor. Na região irreversível todo transporte de corrente elétrica é permitido. Em supercondutores granulares, as medidas de irreversibilidade magnética e resistividade nula não dependem das mesmas partes da amostra. Enquanto, a resistência elétrica depende de um arranjo de grãos que atravessam toda a amostra a irreversibilidade depende de clusters de grãos bem acoplados. Devido a isso, as medidas de resistência nula devem estar em pontos abaixo da linha de irreversibilidade magnética. O objetivo deste trabalho é analisar as medidas de transporte elétrico e magnetização e correlacionar às linhas de resistência nula e as linhas de irreversibilidade magnética, em diferentes orientações de campo-corrente, para uma amostra com a adição de 30% da fase Y211 (Y2BaCuO5) e comparar os dados obtidos com uma amostra na qual foram adicionados 17% desta mesma fase.Postprint (published version

Calcium-based functionalization of carbon nanostructures for peptide immobilization in aqueous media

We predict a covalent functionalization strategy for precise immobilization of peptides on carbon nanostructures immersed in water, based on atomistic first-principles simulations. The proposed strategy consists of straightforward decoration of the carbon nanosurfaces (CNS, e.g. graphene and nanotubes) with calcium atoms. This approach presents a series of improvements with respect to customary covalent CNS functionalization techniques: (i) intense and highly selective biomolecule-CNS interactions are accomplished while preserving atomic CNS periodicity, (ii) under ambient conditions calcium-decorated CNS and their interactions with biomolecules remain strongly attractive both in vacuum and aqueous environment, and (iii) calcium coatings already deplete the intrinsic hydrophobicity of CNS thus additional functionalization for CNS water miscibility is not required. The observed biomolecule-CNS binding enhancement can be explained in terms of large electronic transfers from calcium to the oxygen atoms in the carboxyl and side-chain groups of the peptide. The kind of electronic, structural and thermodynamic properties revealed in this work strongly suggest the potential of Ca-decorated CNS for applications in drug delivery and biomaterials engineering

A redox-active radical as an effective nanoelectronic component: stability and electrochemical tunnelling spectroscopy in ionic liquids

A redox-active persistent perchlorotriphenylmethyl (PTM) radical chemically linked to gold exhibits stable electrochemical activity in ionic liquids. Electrochemical tunnelling spectroscopy in this medium demonstrates that the PTM radical shows a highly effective redox-mediated current enhancement, demonstrating its applicability as an active nanometer-scale electronic component.We acknowledge the financial support from the EU projects ACMOL (FET Young Explorers, GA no. 618082), ERC StG 2012-306826 e-GAMES, ITN iSwitch (GA no. 642196), COST Action TD1002, the Swiss National Science Foundation (Grant No. 200020-144471), the Networking Research Center of Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN), the DGI (Spain) with project BE-WELL CTQ2013-40480-R, the Generalitat de Catalunya with project 2014-SGR-17, and the Severo Ochoa program. N. C acknowledges the RyC program. C. F. is enrolled in the Materials Science PhD program of UAB. We acknowledge support of the publication fee by the CSIC Open Access Publication Support Initiative through its Unit of Information Resources for Research (URICI). Editoria

La restauración ecológica aplicada a la minería a cielo abierto en Cataluña

En la minería a cielo abierto, la revegetación es el objetivo principal de las tareas de restauración ecológica y puede evaluarse desde diferentes enfoques. El aspecto paisajístico ha sido hasta la fecha el más ampliamente valorado y frecuentemente suele asimilarse a la presencia de vegetación que disminuye el impacto visual de estas zonas.La frase 'está verde' simboliza y resume todo un conjunto de prioridades y una primera etapa de implementación de la ley 12/1981 de la legislación catalana.De hecho, naturalizar los taludes resultantes del cese de la extracción de recursos minerales no es una tarea fácil. El tipo de vegetación obtenido difiere en muchos casos de la vegetación de los sistemas natural es del entorno y genera una disfunción en el contexto paisajístico y ecológico [...]