281 research outputs found

    Human-Agent Teamwork in Cyber Operations: Supporting Co-evolution of Tasks and Artifacts with Luna

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    Abstract. In this article, we outline the general concept of coactive emergence, an iterative process whereby joint sensemaking and decision-making activities are undertaken by analysts and software agents. Then we explain our rationale for the development of the Luna software agent framework. In particular, we focus on how we use capabilities for comprehensive policy-based governance to ensure that key requirements for security, declarative specification of task-work, and built-in support for joint activity within mixed teams of humans and agents are satisfied

    Organizational and Leadership Implications for Transformational Development

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    Transformational development is a concept of change that originated in the Christian context but has now become generally used in the work of both secular and faith-based organizations. The growing use of the concept by organizations that are fundamentally different has naturally led to some confusion about what the concept means and what it takes to effectively implement it. In this article, we describe the key features of the concept and how they are important in determining the organizational requirements for its effective implementation. Drawing on a few cases, the paper highlights the centrality of faith in transformational development work

    Multiwavelength studies of MHD waves in the solar chromosphere: An overview of recent results

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    The chromosphere is a thin layer of the solar atmosphere that bridges the relatively cool photosphere and the intensely heated transition region and corona. Compressible and incompressible waves propagating through the chromosphere can supply significant amounts of energy to the interface region and corona. In recent years an abundance of high-resolution observations from state-of-the-art facilities have provided new and exciting ways of disentangling the characteristics of oscillatory phenomena propagating through the dynamic chromosphere. Coupled with rapid advancements in magnetohydrodynamic wave theory, we are now in an ideal position to thoroughly investigate the role waves play in supplying energy to sustain chromospheric and coronal heating. Here, we review the recent progress made in characterising, categorising and interpreting oscillations manifesting in the solar chromosphere, with an impetus placed on their intrinsic energetics.Comment: 48 pages, 25 figures, accepted into Space Science Review

    The BRIDGE HadCM3 family of climate models: HadCM3@Bristol v1.0

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    Understanding natural and anthropogenic climate change processes involves using computational models that represent the main components of the Earth system: the atmosphere, ocean, sea ice, and land surface. These models have become increasingly computationally expensive as resolution is increased and more complex process representations are included. However, to gain robust insight into how climate may respond to a given forcing, and to meaningfully quantify the associated uncertainty, it is often required to use either or both ensemble approaches and very long integrations. For this reason, more computationally efficient models can be very valuable tools. Here we provide a comprehensive overview of the suite of climate models based around the HadCM3 coupled general circulation model. This model was developed at the UK Met Office and has been heavily used during the last 15 years for a range of future (and past) climate change studies, but has now been largely superseded for many scientific studies by more recently developed models. However, it continues to be extensively used by various institutions, including the BRIDGE (Bristol Research Initiative for the Dynamic Global Environment) research group at the University of Bristol, who have made modest adaptations to the base HadCM3 model over time. These adaptations mean that the original documentation is not entirely representative, and several other relatively undocumented configurations are in use. We therefore describe the key features of a number of configurations of the HadCM3 climate model family, which together make up HadCM3@Bristol version 1.0. In order to differentiate variants that have undergone development at BRIDGE, we have introduced the letter B into the model nomenclature. We include descriptions of the atmosphere- only model (HadAM3B), the coupled model with a low-resolution ocean (HadCM3BL), the high-resolution atmosphere- only model (HadAM3BH), and the regional model (HadRM3B). These also include three versions of the land surface scheme. By comparing with observational datasets, we show that these models produce a good representation of many aspects of the climate system, including the land and sea surface temperatures, precipitation, ocean circulation, and vegetation. This evaluation, combined with the relatively fast computational speed (up to 1000 times faster than some CMIP6 models), motivates continued development and scientific use of the HadCM3B family of coupled climate models, predominantly for quantifying uncertainty and for long multi-millennial-scale simulations

    Physicochemical composition of wastes and co-located environmental designations at legacy mine sites in the south west of England and Wales: Implications for their resource potential

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    © 2016 This work examines the potential for resource recovery and/or remediation of metalliferous mine wastes in the south west of England and Wales. It does this through an assessment of the physicochemical composition of several key metalliferous legacy mine waste piles and an analysis of their co-location with cultural, geological and ecological designations. Mine waste samples were taken from 14 different sites and analysed for metal content, mineralogy, paste pH, particle size distribution, total organic carbon and total inorganic carbon. The majority of sites contain relatively high concentrations (in some cases up to several % by mass) of metals and metalloids, including Cu, Zn, As, Pb, Ag and Sn, many of which exceed ecological and/or human health risk guideline concentrations. However, the economic value of metals in the waste could be used to offset rehabilitation costs. Spatial analysis of all metalliferous mine sites in the south west of England and Wales found that around 70% are co-located with at least one cultural, geological and ecological designation. All 14 sites investigated are co-located with designations related to their mining activities, either due to their historical significance, rare species assemblages or geological characteristics. This demonstrates the need to consider the cultural and environmental impacts of rehabilitation and/or resource recovery on such sites. Further work is required to identify appropriate non-invasive methodologies to allow sites to be rehabilitated at minimal cost and disturbance

    Factors affecting body temperatures of toads

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    Factors influencing levels and rates of variation of body temperature ( T b ) in montane Bufo boreas boreas and in lowland Bufo boreas halophilus were investigated as an initial step toward understanding the role of natural thermal variation in the physiology and energetics of these ectothermic animals. Body temperatures of boreas can vary 25–30° C over 24-h periods. Such variation is primarily due to both nocturnal and diurnal activity and the physical characteristics of the montane environment. Bufo boreas halophilus are primarily nocturnal except during breeding and are voluntarily active at body temperatures ranging between 10 and 25° C. Despite variation in T b encountered in the field, boreas select a narrow range of T b in a thermal gradient, averaging 23.5 and 26.2° C for fasted individuals maintained under field conditions or acclimated to 20° C, respectively. In a thermal gradient the mean T b of fasted halophilus acclimated to 20° C is 23.9° C. Skin color of boreas varies in the field from very dark to light. The dark skins absorb approximately 4% more radiation than the light ones. Light colored boreas should absorb approximately 5% more radiation than similarly colored halophilus . Evaporative water losses increase directly with skin temperatures and vapor pressure deficit in both subspecies. Larger individuals heat and cool more slowly than smaller ones. Calculation of an enery budget for boreal toads suggests that they could sit in direct sunlight for long periods without fatally overheating, providing the skin was continually moist.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/47722/1/442_2004_Article_BF00344732.pd

    On the mechanisms governing gas penetration into a tokamak plasma during a massive gas injection

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    A new 1D radial fluid code, IMAGINE, is used to simulate the penetration of gas into a tokamak plasma during a massive gas injection (MGI). The main result is that the gas is in general strongly braked as it reaches the plasma, due to mechanisms related to charge exchange and (to a smaller extent) recombination. As a result, only a fraction of the gas penetrates into the plasma. Also, a shock wave is created in the gas which propagates away from the plasma, braking and compressing the incoming gas. Simulation results are quantitatively consistent, at least in terms of orders of magnitude, with experimental data for a D 2 MGI into a JET Ohmic plasma. Simulations of MGI into the background plasma surrounding a runaway electron beam show that if the background electron density is too high, the gas may not penetrate, suggesting a possible explanation for the recent results of Reux et al in JET (2015 Nucl. Fusion 55 093013)
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