558 research outputs found

    A Comparing Method of Two Team Behaviours in the Simulation Coach Competition

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    Proceeding of: Third International Conference on Modeling Decisions for Artificial Intelligence, MDAI 2006, Tarragona, Spain, April 3-5, 2006.The main goal of agent modelling is to extract and represent the knowledge about the behaviour of other agents. Nowadays, modelling an agent in multi-agent systems is increasingly becoming more complex and significant. Also, robotic soccer domain is an interesting environment where agent modelling can be used. In this paper, we present an approach to classify and compare the behaviour of a multi-agent system using a coach in the soccer simulation domain of the RoboCup.Publicad

    Reproductive Isolation in a Threespine Stickleback Hybrid Zone

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    In many estuarine sites, morphological and genetic differences between anadromous and freshwater threespine sticklebacks are maintained despite breeding in sympatry. Here, we investigate the maintenance of this morphological divergence in a natural hybrid zone in the River Tyne, Scotland. We provide a morphological description of the hybrid zone, and using a Bayesian MCMC approach, identified distinct anadromous and freshwater genetic clusters. Anadromous and freshwater sticklebacks breed in spatial and temporal sympatry in the lower reaches of the River Tyne. The frequency of hybrids within these sites (33%) indicates prezygotic isolation is not complete, and suggests that assortative mating is not strong. However, significant heterozygote deficit and cytonuclear disequilibrium in juveniles collected from sympatric sites confirms that barriers to gene flow exist between the morphs in the wild. In addition, we found no evidence of a directional bias in hybridisation, although hybrids with anadromous mothers were more common because anadromous females outnumbered freshwater females within the hybrid zone. We discuss the potential contribution of temporal, spatial, and sexual prezygotic barriers to the observed reproductive isolation as well as postzygotic selection against hybrid zygotes or fry

    Sexual dimorphism in the size and shape of the raptorial pedipalps of Giant Whip Spiders (Arachnida: Amblypygi)

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    Sexual dimorphism in the form of elaborate crests, horns and swellings can be a clear indicator of the differing evolutionary pressures to which males and females are subject. However, dimorphism can also be expressed in more subtle shape differences not outwardly obvious to the observer. Whip spiders (Amblypygi) possess a unique pair of spined pedipalps hypothesized to primarily function in prey capture, but also serving multiple other functions. Little is known regarding the intraspecific shape variation of these limbs and its potential causes. Because a role during courtship and male contest has also been hypothesized, sexual selection may contribute to shape differences. As such, we hypothesize that sexual dimorphism will be present in the size and shape of amblypygid pedipalps, with male contest selecting for longer and thicker pedipalps, and larger spines in males. This study aims to test this hypothesis, by quantifying the contribution of ontogeny and sexual dimorphism to shape within the raptorial pedipalps of Damon variegatus. Discriminant function analysis using GMM landmark data reveals statistically significant sexual shape dimorphism in both the tibia and femur of the pedipalp. Contrary to our hypothesis, males display a more gracile pedipalp morphology with reduced spination. Sex differences in the allometric slope and overall size were also found in a number of linear appendicular metrics using Type-II regression. Males have statistically longer pedipalp tibiae, whip femora, and leg two femora. We propose that males have evolved a longer pedipalps in the context of display contest rather than physical aggression. The elongation of structures used in display-based contest and courtship found herein further emphasizes the contribution of visual cues to the evolution of morphology more broadly

    Association Mapping Reveals Novel Stem Rust Resistance Loci in Durum Wheat at the Seedling Stage

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    Wheat stem rust rapidly evolves new virulence to resistance genes. Recently emerged races in East Africa, such as TTKSK (or Ug99), possess broad virulence to durum cultivars, and only a limited number of genes provide resistance. An association mapping (AM) study conducted on 183 durum wheat accessions has allowed us to identify 41 quantitative trait loci (QTLs; determination coefficient [R2] values from 1.1 to 23.1%) for seedling resistance to one or more of four highly virulent stem rust races: TRTTF, TTTTF, TTKSK (Ug99), and JRCQC, two of which (TRTTF and JRCQC) were isolated from Ethiopia. Among these loci, 24 are novel, while the remaining 17 overlapped with loci previously shown to provide field resistance in Ethiopia and/or chromosome regions known to harbor designated stem rust resistance designated loci (Sr). The identified loci were either effective against multiple races or race specific, particularly for race JRCQC. Our results highlight that stem rust resistance in durum wheat is governed in part by loci for resistance across multiple races, and in part by race-specific ones (23 and 18, respectively). Collectively, these results provide useful information to improve the effectiveness of marker-assisted selection towards the release of durum wheat cultivars with durable stem rust resistance

    The Morphometric Synthesis for landmarks and edge-elements in images

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    Over the last decade, techniques from mathematical statistics, multivariate biometrics, non-Euclidean geometry, and computer graphics have been combined in a coherent new system of tools for the biometric analysis of landmarks , or labelled points, along with the biological images in which they are seen. Multivariate analyses of samples for all the usual scientific purposes - description of mean shapes, of shape variation, and of the covariation of shape with size, group, or other causes or effects - may be carried out very effectively in the tangent space to David Kendall's shape space at the Procrustes average shape. For biometric interpretation of such analyses, we need a basis for the tangent space that is Procrustes-orthonormal, and we need graphics for visualizing mean shape differences and other segments and vectors there; both of these needs are managed by the thin-plate spline. The spline also links the biometrics of landmarks to deformation analysis of curves in the images from which the landmarks originally arose. This article reviews the principal tools of this synthesis in a typical study design involving landmarks and edge information from a microfossil.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/75091/1/j.1365-3121.1995.tb00535.x.pd
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