1,867 research outputs found

    Integrated risk/cost planning models for the US Air Traffic system

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    A prototype network planning model for the U.S. Air Traffic control system is described. The model encompasses the dual objectives of managing collision risks and transportation costs where traffic flows can be related to these objectives. The underlying structure is a network graph with nonseparable convex costs; the model is solved efficiently by capitalizing on its intrinsic characteristics. Two specialized algorithms for solving the resulting problems are described: (1) truncated Newton, and (2) simplicial decomposition. The feasibility of the approach is demonstrated using data collected from a control center in the Midwest. Computational results with different computer systems are presented, including a vector supercomputer (CRAY-XMP). The risk/cost model has two primary uses: (1) as a strategic planning tool using aggregate flight information, and (2) as an integrated operational system for forecasting congestion and monitoring (controlling) flow throughout the U.S. In the latter case, access to a supercomputer is required due to the model's enormous size

    Possible Implications of Mandating Choice in Corporate Defined Benefit Plans

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    Defined benefit (DB) plans have been applauded as the mainstay of the US pension system for many years, but increasingly such plans have been replaced with defined contribution (DC) pensions. One exception to the downward DB spiral has been the development of “hybrid” plans. Technically, these are pensions where the benefit accrual is communicated as a lump sum and not in the form of an annuity as is done with traditional pensions. In the transition to this new plan structure, some employees at some firms have contended that they would have accumulated retirement benefits more quickly under the old DB plan – assuming they remained employed – than under the new hybrid design. In response, some legislators have attempted to force companies transitioning from a traditional DB to a hybrid plan to offer all workers the open-ended choice of remaining in the old DB plan, versus switching to the new hybrid plan. In this paper we explore some of the possible consequences of mandating plan choice in this fashion. We conclude that regulators seeking to mandate pension choice should take into account the potential undesirable outcomes of such a law

    A preliminary investigation into psychophysiological effects of threatening a perceptually embodied rubber hand in healthy human participants

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    Background and aims: Threatening a perceptually embodied rubber hand with noxious stimuli has been shown to generate levels of anxiety similar to that experienced when a real hand is threatened. The aim of this study was to investigate skin conductance response, self-reported anxiety and the incidence, type and location of sensations when a perceptually embodied rubber was exposed to threatening and non-threatening stimuli. Methods: A repeated measures cross-over design was used whereby 20 participants (>18 years, 14 females) received a threatening (syringe needle) and non-threatening (soft brush) stimulus to a perceptually embodied rubber hand. Perceptual embodiment was achieved using a soft brush to synchronously stroke the participant’s real hand (out of view) and a rubber hand (in view). Then the investigator approached the rubber hand with a syringe needle (threat) or soft brush (non-threat). Results: Repeated measures ANOVA found that approaching the perceptually embodied rubber hand with either stimulus produced statistically significant reductions in the rated intensity of response to the following questions (p<0.01): ‘How strongly does it feel like the rubber hand is yours?’; ‘How strongly does it feel like the rubber hand is part of your body?’; and ‘How strongly does it feel you can move the rubber hand?’. However, there were no statistically significant differences in scores between needle and brush stimuli. Repeated measures ANOVA on skin conductance response found statistically significant effects for experimental Events (baseline; stroking; perceptual embodiment; stimuli approaching rubber hand; stimuli touching rubber hand; p<0.001) but not for Condition (needle versus brush p=0.964) or experimental Event x Condition interaction (p=0.160). Ten of the 20 participants (50%) reported that they experienced a sensation arising from the rubber hand when the rubber hand was approached and touched by either the needle and/or brush but these sensations lacked precision in location, timing, and nature. Conclusion and Implications: Our preliminary findings suggest that the increase in arousal in response to stimuli entering the peripersonal space may not be selective for threat. There was tentative evidence that more intense sensations were experienced when a perceptually embodied rubber hand was approached by a threatening stimulus. Our findings provide initial insights and should serve as a catalyst for further research

    Justice Policy Reform for High-Risk Juveniles: Using Science to Achieve Large-Scale Crime Reduction

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    After a distinctly punitive era, a period of remarkable reform in juvenile crime regulation has begun. Practical urgency has fueled interest in both crime reduction and research on the prediction and malleability of criminal behavior. In this rapidly changing context, high-risk youth – the small proportion of the population where crime is concentrated – present a conundrum. Research indicates that these are precisely the individuals to intensively treat to maximize crime reduction, but there are both real and imagined barriers to doing so. Institutional placement or criminal court processing can exclude these youths from interventions that would better protect public safety. In this article, we synthesize relevant research to help resolve this challenge in a manner that is consistent with the law’s core principles. In our view, adolescence offers unique opportunities for risk reduction that could (with modifications) be realized in the juvenile justice system in cooperation with other social institutions

    Properties of the Scalar Universal Equations

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    The variational properties of the scalar so--called ``Universal'' equations are reviewed and generalised. In particular, we note that contrary to earlier claims, each member of the Euler hierarchy may have an explicit field dependence. The Euler hierarchy itself is given a new interpretation in terms of the formal complex of variational calculus, and is shown to be related to the algebra of distinguished symmetries of the first source form.Comment: 15 pages, LaTeX articl
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