1,609 research outputs found

    Mechanisms of Individual Differences in Impulsive and Risky Choice in Rats

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    Citation: Kirkpatrick, K., Marshall, A. T., & Smith, A. P. (2015). Mechanisms of Individual Differences in Impulsive and Risky Choice in Rats. Comparative Cognition & Behavior Reviews, 10. Retrieved from http://comparative-cognition-and-behavior-reviews.org/2015/vol10_kirkpatrick_marshall_smith/Mechanisms of Individual Differences in Impulsive and Risky Choice in Rats Kimberly Kirkpatrick Department of Psychological Sciences, Kansas State University Andrew T. Marshall Department of Psychological Sciences, Kansas State University Aaron P

    Community Insurgency: Constituency, School Choice, and the Common Good

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    This study explores the ways in which the democratic notion of the people may be enacted in the school choice arena. Through an investigation of a charter school movement in a rural and segregated district in the Deep South, we explore themes of the constituent paradox that enabled the community to move beyond individual interests towards an expression of the common good. It is argued that for the people to be invoked via the democratic claim, they must identify more deeply than the institutions of their representation and recognize an expanded form of individualism defined through participation over consumption

    Individual differences in impulsive and risky choice: effects of environmental rearing conditions

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    The present experiment investigated early-rearing environment modulation of individual differences in impulsive and risky choice. Rats were reared in an isolated condition (IC; n = 12), in which they lived alone without novel stimuli, or an enriched condition (EC; n = 12), in which they lived among conspecifics with novel stimuli. The impulsive choice task involved choices between smaller-sooner (SS) versus larger-later (LL) rewards. The risky choice task involved choices between certain-smaller (C-S) versus uncertain-larger (U-L) rewards. Following choice testing, incentive motivation to work for food was measured using a progressive ratio task and correlated with choice behavior. HPLC analyses were conducted to determine how monoamine concentrations within the prefrontal cortex (PFC) and nucleus accumbens (NAC) related to behavior in different tasks. IC rats were more impulsive than EC rats, but they did not differ in risky choice behavior. However, choice behavior across tasks was significantly correlated (i.e., the more impulsive rats were also riskier). There were no group differences in monoamine levels, but noradrenergic and serotonergic concentrations were significantly correlated with impulsive and risky choice. Furthermore, serotonin and norepinephrine concentrations in the NAC significantly correlated with incentive motivation and the timing of the reward delays within the choice tasks. These results suggest a role for domain general processes in impulsive and risky choice and indicate the importance of the NAC and/or PFC in timing, reward processing, and choice behavior

    Nonlinear Analysis and Preliminary Testing Results of a Hybrid Wing Body Center Section Test Article

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    A large test article was recently designed, analyzed, fabricated, and successfully tested up to the representative design ultimate loads to demonstrate that stiffened composite panels with through-the-thickness reinforcement are a viable option for the next generation large transport category aircraft, including non-conventional configurations such as the hybrid wing body. This paper focuses on finite element analysis and test data correlation of the hybrid wing body center section test article under mechanical, pressure and combined load conditions. Good agreement between predictive nonlinear finite element analysis and test data is found. Results indicate that a geometrically nonlinear analysis is needed to accurately capture the behavior of the non-circular pressurized and highly-stressed structure when the design approach permits local buckling

    Testing and Analysis of a Composite Non-Cylindrical Aircraft Fuselage Structure

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    The Environmentally Responsible Aviation Project aimed to develop aircraft technologies enabling significant fuel burn and community noise reductions. Small incremental changes to the conventional metallic alloy-based 'tube and wing' configuration were not sufficient to achieve the desired metrics. One airframe concept identified by the project as having the potential to dramatically improve aircraft performance was a composite-based hybrid wing body configuration. Such a concept, however, presented inherent challenges stemming from, among other factors, the necessity to transfer wing loads through the entire center fuselage section which accommodates a pressurized cabin confined by flat or nearly flat panels. This paper discusses a finite element analysis and the testing of a large-scale hybrid wing body center section structure developed and constructed to demonstrate that the Pultruded Rod Stitched Efficient Unitized Structure concept can meet these challenging demands of the next generation airframes. Part II of the paper considers the final test to failure of the test article in the presence of an intentionally inflicted severe discrete source damage under the wing up-bending loading condition. Finite element analysis results are compared with measurements acquired during the test and demonstrate that the hybrid wing body test article was able to redistribute and support the required design loads in a severely damaged condition
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