2,697 research outputs found

    Swarming Reconnaissance Using Unmanned Aerial Vehicles in a Parallel Discrete Event Simulation

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    Current military affairs indicate that future military warfare requires safer, more accurate, and more fault-tolerant weapons systems. Unmanned Aerial Vehicles (UAV) are one answer to this military requirement. Technology in the UAV arena is moving toward smaller and more capable systems and is becoming available at a fraction of the cost. Exploiting the advances in these miniaturized flying vehicles is the aim of this research. How are the UAVs employed for the future military? The concept of operations for a micro-UAV system is adopted from nature from the appearance of flocking birds, movement of a school of fish, and swarming bees among others. All of these natural phenomena have a common thread: a global action resulting from many small individual actions. This emergent behavior is the aggregate result of many simple interactions occurring within the flock, school, or swarm. In a similar manner, a more robust weapon system uses emergent behavior resulting in no weakest link because the system itself is made up of simple interactions by hundreds or thousands of homogeneous UAVs. The global system in this research is referred to as a swarm. Losing one or a few individual unmanned vehicles would not dramatically impact the swarms ability to complete the mission or cause harm to any human operator. Swarming reconnaissance is the emergent behavior of swarms to perform a reconnaissance operation. An in-depth look at the design of a reconnaissance swarming mission is studied. A taxonomy of passive reconnaissance applications is developed to address feasibility. Evaluation of algorithms for swarm movement, communication, sensor input/analysis, targeting, and network topology result in priorities of each model\u27s desired features. After a thorough selection process of available implementations, a subset of those models are integrated and built upon resulting in a simulation that explores the innovations of swarming UAVs

    Like artificial trees? The effect of framing by natural analogy on public perceptions of geoengineering

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    The linguistic frames used to describe new areas of science and technology can have a powerful effect on the way that those technologies are perceived by the general public. As geoengineering continues to attract scholarly and policy interest, a number of frames have emerged in the scientific, political and media discourse. In the current paper, we provide an empirical test of one of the most prevalent framing devices: describing geoengineering technologies by analogy to natural processes. In an online experiment with members of the UK public, participants who read a description of geoengineering technologies as analogous to natural processes were more likely to support geoengineering as a response to climate change. In addition, participants’ views about the relationship between geoengineering and nature strongly predicted support for geoengineering. Our findings suggest that communicators should be cautious when using natural analogies to communicate about geoengineering with the general public, as frame choice is likely to influence public attitudes and potentially convey undue positivity

    Exploring experiences of cancer care in Wales: a thematic analysis of free-text responses to the 2013 Wales Cancer Patient Experience Survey (WCPES)

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    Objectives To provide the first systematic analysis of a national (Wales) sample of free-text comments from patients with cancer, to determine emerging themes and insights regarding experiences of cancer care in Wales. Design Thematic analysis of free-text data from a population-based survey. Setting and participants Adult patients with a confirmed cancer diagnosis treated within a 3-month period during 2012 in the 7 health boards and 1 trust providing cancer care in Wales. Main outcome measures Free-text categorised by theme, coded as positive or negative, with ratios. Overarching themes are identified incorporating comment categories. Methods 4672 respondents (of n=7352 survey respondents) provided free-text comments. Data were coded using a multistage approach: (1) coding of comments into general categories (eg, nursing, surgery, etc), (2) coding of subcategories within main categories (eg, nursing care, nursing communication, etc), (3) cross-sectional analysis to identify themes cutting across categories, (4) mapping of categories/subcategories to corresponding closed questions in the Wales Cancer Patient Experience Survey (WCPES) data for comparison. Results Most free-text respondents (82%, n 3818) provided positive comments about their cancer care, with 49% (n=2313) giving a negative comment (ratio 0.6:1, negative-to-positive). 3172 respondents (67.9% of free-text respondents) provided a comment mapping to 1 of 4 overarching themes: communication (n=1673, 35.8% free-text respondents, a ratio of 1.0:1); waiting during the treatment and/or post-treatment phase (n=923, 19.8%, ratio 1.5:1); staffing and resource levels (n=671, 14.4% ratio 5.3:1); speed and quality of diagnostic care (n=374, 8.0%, ratio 1.5:1). Within these areas, constituent subthemes are discussed. Conclusions This study presents specific areas of concern for patients with cancer, and reveals a number of themes present across the cancer journey. While the majority of comments were positive, analysis reveals concerns shared by significant numbers of respondents. Timely communication can help to manage these anxieties, even where delays or difficulties in treatment may be encountered

    Pleistocene Bats (Late Irvingtonian and Late Rancholabrean) from Nuckolls and Sherman Counties, Nebraska

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    We document rare finds of fossil bats from two localities representing the Pleistocene epoch in southern and central Nebraska, Albert Ahrens locality (No-104, late Irvingtonian age, Middle Pleistocene), Nuckolls County, and Litchfield (Sm-102, late Rancholabrean age, latest Pleistocene), Sherman County. The Albert Ahrens local fauna with strong boreal influence has produced two bats, Lasiurus cf. borealis and Cf. Myotis sp. The Litchfield local fauna, also showing a strong boreal influence, has yielded two bats, Eptesicus fuscus and Cf. Myotis, among a diverse Pleistocene fauna of small vertebrates and a pollen record indicating a boreal mixed conifer and deciduous woodland, contrasting with the grassland and mixed grass prairie of the area in historic times prior to anthropogenic conversion. The vertebrate fauna from the Litchfield site can be assigned to the Rancholabrean land mammal age based on the presence of Bison, on faunal correlation, and on several extralimital taxa of small mammals. The fossil bat taxa are widespread in North America and still extant in Nebraska today; their glacial stage occurrences in a nonkarstic (caveless) region is consistent with previous interpretations of the Albert Ahrens and Litchfield local faunas as indicating cool equable climates and wooded parkland environments. These are the first bats to be reported from each of the respective paleofaunas

    Shooting Alone: The Pre-Attack Experiences and Behaviors of U.S. Solo Mass Murderers with Implications for Threat Assessments

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    This paper outlines the socio-demographic, developmental, antecedent attack, attack preparation and commission properties of 115 mass murderers between 1990 and 2014. The results indicate that mass murderer attacks are usually the culmination of a complex mix of personal, political and social drivers that crystalize at the same time to drive the individual down the path of violent action. We specifically focus upon areas related to prior criminal engagement, leakage and attack location familiarity. Whether the violence comes to fruition is usually a combination of the availability and vulnerability of suitable targets that suit the heady mix of personal and political grievances and the individual’s capability to engage in an attack from both a psychological and technical capability standpoint. Many individual cases share a mixture of unfortunate personal life circumstances coupled with an intensification of beliefs/grievances that later developed into the idea to engage in violence

    Multi-Pulse Laser Wakefield Acceleration: A New Route to Efficient, High-Repetition-Rate Plasma Accelerators and High Flux Radiation Sources

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    Laser-driven plasma accelerators can generate accelerating gradients three orders of magnitude larger than radio-frequency accelerators and have achieved beam energies above 1 GeV in centimetre long stages. However, the pulse repetition rate and wall-plug efficiency of plasma accelerators is limited by the driving laser to less than approximately 1 Hz and 0.1% respectively. Here we investigate the prospects for exciting the plasma wave with trains of low-energy laser pulses rather than a single high-energy pulse. Resonantly exciting the wakefield in this way would enable the use of different technologies, such as fibre or thin-disc lasers, which are able to operate at multi-kilohertz pulse repetition rates and with wall-plug efficiencies two orders of magnitude higher than current laser systems. We outline the parameters of efficient, GeV-scale, 10-kHz plasma accelerators and show that they could drive compact X-ray sources with average photon fluxes comparable to those of third-generation light source but with significantly improved temporal resolution. Likewise FEL operation could be driven with comparable peak power but with significantly larger repetition rates than extant FELs
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