A Spatial Agent-Based Model of N-Person Prisoner's Dilemma Cooperation in a Socio-Geographic Community

The purpose of this paper is to present a spatial agent-based model of N-person prisoner's dilemma that is designed to simulate the collective communication and cooperation within a socio-geographic community. Based on a tight coupling of REPAST and a vector Geographic Information System, the model simulates the emergence of cooperation from the mobility behaviors and interaction strategies of citizen agents. To approximate human behavior, the agents are set as stochastic learning automata with Pavlovian personalities and attitudes. A review of the theory of the standard prisoner's dilemma, the iterated prisoner's dilemma, and the N-person prisoner's dilemma is given as well as an overview of the generic architecture of the agent-based model. The capabilities of the spatial N-person prisoner's dilemma component are demonstrated with several scenario simulation runs for varied initial cooperation percentages and mobility dynamics. Experimental results revealed that agent mobility and context preservation bring qualitatively different effects to the evolution of cooperative behavior in an analyzed spatial environment.Agent Based Modeling, Cooperation, Prisoners Dilemma, Spatial Interaction Model, Spatially Structured Social Dilemma, Geographic Information Systems

Hobbes and the Congo: Frames, Local Violence, and International Intervention

Why do international peacebuilders fail to address the local causes of peace process failures? The existing explanations of peacebuilding failures, which focus on constraints and vested interests, do not explain the international neglect of local conflict. In this article, I show how discursive frames shape international intervention and preclude international action on local violence. Drawing on more than 330 interviews, multi-sited ethnography, and document analysis, I develop a case study of the Democratic Republic of Congo's transition from war to peace and democracy (2003-2006). I demonstrate that local agendas played a decisive role in sustaining local, national, and regional violence. However, a postconflict peacebuilding frame shaped the international understanding of violence and intervention in such a way that local conflict resolution appeared irrelevant and illegitimate. This frame included four key elements: international actors labeled the Congo a "postconflict" situation; they believed that violence there was innate and therefore acceptable even in peacetime; they conceptualized international intervention as exclusively concerned with the national and international realms; and they saw holding elections, as opposed to local conflict resolution, as a workable, appropriate, and effective tool for state- and peacebuilding. This frame authorized and justified specific practices and policies while precluding others, notably local conflict resolution, ultimately dooming the peacebuilding efforts. In conclusion, I contend that analyzing discursive frames is a fruitful approach to the puzzle of international peacebuilding failures beyond the Congo

Effects of rhythm on memory for spoken sequences : a model and tests of its stimulus-driven mechanism

Immediate memory for spoken sequences depends on their rhythm – different levels of accuracy and patterns of error are seen according to the way in which items are spaced in time. Current models address these phenomena only partially or not at all. We investigate the idea that temporal grouping effects are an emergent property of a general serial ordering mechanism based on a population of oscillators locally-sensitive to amplitude modulations on different temporal scales. Two experiments show that the effects of temporal grouping are independent of the predictability of the grouping pattern, consistent with this model’s stimulus-driven mechanism and inconsistent with alternative accounts in terms of top-down processes. The second experiment reports detailed and systematic differences in the recall of irregularly grouped sequences that are broadly consistent with predictions of the new model. We suggest that the bottom-up multi-scale population oscillator (or BUMP) mechanism is a useful starting point for a general account of serial order in language processing more widely

Hydrokinetic Turbine Effects on Fish Swimming Behaviour

Hydrokinetic turbines, targeting the kinetic energy of fast-flowing currents, are under development with some turbines already deployed at ocean sites around the world. It remains virtually unknown as to how these technologies affect fish, and rotor collisions have been postulated as a major concern. In this study the effects of a vertical axis hydrokinetic rotor with rotational speeds up to 70 rpm were tested on the swimming patterns of naturally occurring fish in a subtropical tidal channel. Fish movements were recorded with and without the rotor in place. Results showed that no fish collided with the rotor and only a few specimens passed through rotor blades. Overall, fish reduced their movements through the area when the rotor was present. This deterrent effect on fish increased with current speed. Fish that passed the rotor avoided the near-field, about 0.3 m from the rotor for benthic reef fish. Large predatory fish were particularly cautious of the rotor and never moved closer than 1.7 m in current speeds above 0.6 ms-1. The effects of the rotor differed among taxa and feeding guilds and it is suggested that fish boldness and body shape influenced responses. In conclusion, the tested hydrokinetic turbine rotor proved non-hazardous to fish during the investigated conditions. However, the results indicate that arrays comprising multiple turbines may restrict fish movements, particularly for large species, with possible effects on habitat connectivity if migration routes are exploited. Arrays of the investigated turbine type and comparable systems should therefore be designed with gaps of several metres width to allow large fish to pass through. In combination with further research the insights from this study can be used for guiding the design of hydrokinetic turbine arrays where needed, so preventing ecological impacts

Co-Flowering Species Richness Increases Pollinator Visitation to Apple Flowers

Co-flowering plants can experience an array of interactions, ranging from facilitation to competition, the direction and strength of which are often dependent on the relative abundance and diversity of the plant species involved and the foraging behavior of their pollinators. Understanding interactions between plant−pollinator networks and how they change over time is particularly important within agricultural systems, such as apples, that flower en masse and that also contain non-crop co-flowering species both within the farm and the surrounding landscape. We determined the degree of overlap between pollinator networks on two varieties of apple (Granny Smith and Pink Lady) and co-flowering plant species within orchards and the wider vegetation matrix in two apple-growing regions (Orange and Bilpin) in Australia. We surveyed plant−pollinator interactions at key stages of the cropping cycle: before mass flowering; during king, peak and late blooms; and, finally, once apple flowering had finished. Overall, we found considerable overlap in the flower visitor assemblage on apples and co-flowering species within the orchard. The introduced honeybee (Apis mellifera) was the most frequent flower visitor to all three vegetation types at all times in Orange. However, in Bilpin, both a native stingless bee (Tetragonula carbonaria) and A. mellifera were highly frequent visitors, both on- and off-crop. Numerous native bees, flies and Lepidoptera also commonly visited apple and co-flowering species within orchards in both locations. We found that native-bee and honeybee visitation to apple flowers was positively correlated with co-flowering species richness (within the orchard and the wider matrix); however, visitation by native bees decreased as the area of co-flowering species in the surrounding landscape increased. Our study highlights the importance of maintaining diverse co-flowering plant communities within the local landscape to increase and support a wide variety of pollinators in horticultural production systems

Co-flowering plants support diverse pollinator populations and facilitate pollinator visitation to sweet cherry crops

Many food crops depend on animal pollination to set fruit. In light of pollinator declines there is growing recognition of the need for agro-ecosystems that can sustain wild pollinator populations, ensuring fruit production and pollinator conservation into the future. One method of supporting resident wild pollinator populations within agricultural landscapes is to encourage and maintain floral diversity. However, pollinator visitation to crop plants can be affected either positively (facilitation) or negatively (competition) by the presence of co-flowering plants. The strength and direction of the facilitative/competitive relationship is driven by multiple factors, including floral abundance and the degree of overlap in pollinator visitation networks. We sought to determine how plant-pollinator networks, within and surrounding sweet cherry (Prunus avium) orchards, change across key time points during the cherry flowering season, in three growing regions in Australia. We found significant overlap in the suite of flower visitors, with seven taxa (including native bees, flies, hoverflies and introduced honey bees, Apis mellifera) observed visiting cherry and other co-flowering species within the orchard and/or the wider surrounding matrix. We found evidence of pollinator facilitation with significantly more total cherry flower visits with increasing percent cover of co-flowering plants within the wider landscape matrix and increased visitation to cherry by honey bees with increasing co-flowering plant richness within the orchard. During the cherry flowering period there was a significant positive relationship between pollinator richness on cherry and pollinator richness on co-flowering plants within the orchard and the area of native vegetation surrounding orchards. Outside of the crop flowering season, co-flowering plants within the orchard and wider landscape matrix supported the same pollinator taxa that were recorded visiting cherry when the crop was flowering. This shows wild plants help support the pollinators important to crop pollination, outside of the crop flowering season, highlighting the role of co-flowering plants within pollinator-dependent cropping systems

No evidence for association of body mass index with salivary amylase gene copy number in the UK 1958 Birth Cohort

ObjectiveIn a 2014 publication, evidence was presented supporting the association of BMI with the copy number of the salivary amylase 1 (AMY1) gene, with an unprecedented effect size of −0.15 kg/m2 (SE 0.02) per copy of AMY1. Most well‐powered attempts to reproduce these findings have not been successful. However, because of different study designs, a significant association may still apply under restricted conditions such as in particular age groups. This study specifically tested the BMI‐AMY1 association at different age points in the same individuals using longitudinal BMI information from participants in the UK 1958 Birth Cohort study.MethodsThis study measured the AMY1 copy number by paralogue ratio tests in genomic DNA and by using array comparative genomic hybridization data. BMI data from 1958 Birth Cohort participants were available from eight different age points between 7 and 50 years.ResultsNo evidence, even at nominal significance, was found for association of the AMY1 copy number with BMI at any age point in approximately 1,400 members of the 1958 Birth Cohort or in 2,835 people from two disease cohorts from the Wellcome Trust Case Control Consortium.ConclusionsThe results do not support an association between BMI and AMY1 copy number at any age point

LBT SHARK-VIS Observes a Major Resurfacing Event on Io

Since volcanic activity was first discovered on Io from Voyager images in 1979, changes on Io's surface have been monitored from both spacecraft and ground-based telescopes. Here, we present the highest spatial resolution images of Io ever obtained from a ground-based telescope. These images, acquired by the SHARK-VIS instrument on the Large Binocular Telescope, show evidence of a major resurfacing event on Io's trailing hemisphere. When compared to the most recent spacecraft images, the SHARK-VIS images show that a plume deposit from a powerful eruption at Pillan Patera has covered part of the long-lived Pele plume deposit. Although this type of resurfacing event may be common on Io, few have been detected due to the rarity of spacecraft visits and the previously low spatial resolution available from Earth-based telescopes. The SHARK-VIS instrument ushers in a new era of high resolution imaging of Io's surface using adaptive optics at visible wavelengths.Comment: 15 pages, 4 figure

Towards a global history of the Unidad Popular

Our understanding of the international and transnational history of Chile during the Unidad Popular (UP) government has expanded considerably since the early 2010s. But what has new research contributed to our understanding of events in Chile and Chile’s significance in a global context? Examining the historiographical advances and questions that have driven scholarship in recent years, this article argues that international and transnational studies that focus attention on Chile and Chileans can offer new perspectives on the rise and fall of the UP. Rather than reducing international histories to an account of a select group of foreigners acting on an empty Chilean stage, these approaches foreground local actors and processes, exploring the extent to which Chileans were shaped by a multiplicity of interactions, invitations and inspirations across borders. Localising the global in this way can help us understand the reasons many within Chile conceptualised their goals, projects and actions as they did. It challenges the idea of Chilean exceptionalism. It also undermines right-wing actors’ claims to be acting solely within national frameworks by revealing their own entanglements in translational networks and intellectual imports. Suggesting that we have much still to learn, the article also highlights possible avenues for further research and reflects on the contemporary relevance of the global in Chilean political discourse today