6,252 research outputs found

    Social learning mechanisms compared in a simple environment

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    Social learning can be adaptive, but little is known about the underlying mechanisms. Many researchers have focused on imitation but this may have led to simpler mechanisms being underestimated. We demonstrate in simulation that imitative learning is not always the best strategy for a group-living animal, and that the effectiveness of any such strategy will depend on details of the environment and the animal's lifestyle. We show that observations of behavioural convergence or "traditions" might suggest effective social learning, but are meaningless considered alone

    Effects of the topology of social networks on information transmission

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    Social behaviours cannot be fully understood without considering the network structures that underlie them. Developments in network theory provide us with relevant modelling tools. The topology of social networks may be due to selection for information transmission. To investigate this, we generated network topologies with varying proportions of random connections and degrees of preferential attachment. We simulated two social tasks on these networks: a spreading innovation model and a simple market. Results indicated that non-zero levels of random connections and low levels of preferential attachment led to more efficient information transmission. Theoretical and practical implications are discussed

    Thermodynamic anomalies in a lattice model of water: Solvation properties

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    We investigate a lattice-fluid model of water, defined on a 3-dimensional body-centered cubic lattice. Model molecules possess a tetrahedral symmetry, with four equivalent bonding arms. The model is similar to the one proposed by Roberts and Debenedetti [J. Chem. Phys. 105, 658 (1996)], simplified by removing distinction between "donors" and "acceptors". We focus on solvation properties, mainly as far as an ideally inert (hydrophobic) solute is concerned. As in our previous analysis, devoted to neat water [J. Chem. Phys. 121, 11856 (2004)], we make use of a generalized first order approximation on a tetrahedral cluster. We show that the model exhibits quite a coherent picture of water thermodynamics, reproducing qualitatively several anomalous properties observed both in pure water and in solutions of hydrophobic solutes. As far as supercooled liquid water is concerned, the model is consistent with the second critical point scenario.Comment: 12 pages, 9 figures, 1 tabl

    Pleading with the Emperor: Pax Americana and the Transformation of Environmental Governance

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    The combined effects of the globalisation and integration of productive networks of capital, the hegemony of neo-liberal discourse in the framing of policy toward capital markets, the unchallenged dominance of the US military, the establishment of the International Monetary Fund (IMF), World Bank (WB) and World Trade Organisation (WTO), and the more recent signing of bilateral free trade agreements(BITs) have circumscribed the ability of governments to exercise sovereignty in the creation of environmental policy. The resultant capacity to "insulate policy from the chaos of politics" (Economist 1994, 9) has prompted a number of authors to situate issues of global governance within the context of Empire. In this paper, we chart the re-emergence of Empire as concept and phenomena. In the first section, we identify three schools of thought that invoke the concept of Empire: the image of Pax Americana held by US neoconservatives for whom Empire is a reality justified by the necessities of geo-political power; the liberal-humanitarianism of European foreign policy elites who argue for a multi-polar Empire to balance American power; and the complex multi-dimensional entity of domination depicted by the global justice movement. We reveal the tensions that exist between Empire’s agents, most notably between a vision of a multi-polar Empire and that of Pax Americana. Through the work of Hardt and Negri, Harvey and Foucault, we develop an operational concept of Empire to explore how the tensions between the agents of Empire manifest as a global system of governance. Drawing on this analysis, we discuss the implications of Empire for environmental politics and policy through a case-study of the Australian-United States Free Trade Agreement (AUSFTA) to illustrate the complex, multiform strategies of power operating in the maintenance and transformation of Empire
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