984 resultados para U.S. Army Research Laboratory.
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This study concerns the application of a model of effective interpersonal relationships to problems arising from staff assessment at I.C.I. Ltd. Corporate Laboratory between 1972 and 1974. In collaboration with academic and industrial supervision, the study commenced with a survey of management and supervisor opinions about the effectiveness of current staff (work) relationships, with particular reference to the problem of recognising and developing creative potential. This survey emphasised a need to improve the relationships between staff in the staff assessment context. A survey of research into creativity emphasised the importance of the interpersonal environment for obtaining creative behaviour in an organisation context. A further survey of theories of how interpersonal behaviour related to personal creativity (therapeutic psychology) provided a model of effective interpersonal behaviour (Carkhuff, 1969) that could be applied to the organisation context of staff assessment. The objective of the project was redefined as a need to improve the conditions of interpersonal behaviour in relation to certain (career development) problems arising from staff assessment practices. In order to demonstrate the application of the model of effective interpersonal behaviour, the research student recorded interviews between himself and members of staff designed to develop and operate the dimensions of the model. Different samples of staff were used to develop the 'facilitative' and the 'action oriented' dimensions of bahaviour, and then for the operation of a helping programme (based on vocational guidance tests). These interactions have been analysed, according to the scales of measurement in the model ana the results are presented in case study form in this thesis. At each stage of the project, results and conclusions were presented to the sponsoring organisation (e.g. industrial supervisor) in order to assess their (subjective) opinion of relevance to the organ isation. Finally, recommendations on further actions towards general improvement of the work relationships in the laboratory were presented in a brief report to the sponsor.
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Malaria is a threat to United States military personnel operating in endemic areas, from which there have been hundreds of cases reported over the past decade. Each of these cases might have been avoided with proper adherence to malaria chemoprophylaxis medications. Military operations may detract from the strict 100% adherence required of these preventive medications. However, the reasons for non-adherence in military populations are not well understood. This behavior was investigated using a cross sectional study design on a convenience sample of U.S. Army Ranger volunteers (n=150) located at three military instillations. Theoretical support was based on components of the Health Belief Model, the Theory of Reasoned Action/Theory of Planned Behavior, and the Social Cognitive Theory. ^ Data on knowledge, attitudes, and practices, as well as multiple environmental domains was collected using an original yet unvalidated questionnaire. The data was analyzed using bivariate Pearson correlations, binary logistic regression, and moderated logistic regressions employing a 0.05 criterion of statistical significance. Power analyses predicted 96-98% power for this analysis. ^ Multiple significant medium strength Pearson correlation coefficients were identified relative to the two dependent variables Take medications as directed and Intend to take the medications as directed the next time. Binary logistic regression analyses identified multiple variables that may predict behavioral intentions to adhere to these preventive medications, as a proxy for behavioral change. Moderated logistic regression analyses identified Command Support for adherence to these medications as a potential significant moderator that interacts with independent variables within three domains of the survey questionnaire. ^ The findings indicate that there may be potential significant beneficial effects, which may improve this behavior in this population of Rangers through 1) promoting affirmative interpersonal communications that emphasize adherence to these medications, 2) including malaria chemoprophylaxis medications in the mission planning process, and 3) military command support, in the form of including the importance of proper adherence to these medications in the unit safety briefings.^
U.S. Army meteorologist Private Merle Coleman at White Sands Missile Range in Las Cruces, New Mexico
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General note: Title and date provided by Bettye Lane.
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General note: Title and date provided by Bettye Lane.
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General note: Title and date provided by Bettye Lane.
Construction of invisibility cloaks of arbitrary shape and size using planar layers of metamaterials
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Transformation optics (TO) is a powerful tool for the design of electromagnetic and optical devices with novel functionality derived from the unusual properties of the transformation media. In general, the fabrication of TO media is challenging, requiring spatially varying material properties with both anisotropic electric and magnetic responses. Though metamaterials have been proposed as a path for achieving such complex media, the required properties arising from the most general transformations remain elusive, and cannot implemented by state-of-the-art fabrication techniques. Here, we propose faceted approximations of TO media of arbitrary shape in which the volume of the TO device is divided into flat metamaterial layers. These layers can be readily implemented by standard fabrication and stacking techniques. We illustrate our approximation approach for the specific example of a two-dimensional, omnidirectional "invisibility cloak", and quantify its performance using the total scattering cross section as a practical figure of merit. © 2012 American Institute of Physics.
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The ability to render objects invisible with a cloak that fits all objects and sizes is a long-standing goal for optical devices. Invisibility devices demonstrated so far typically comprise a rigid structure wrapped around an object to which it is fitted. Here we demonstrate smart metamaterial cloaking, wherein the metamaterial device not only transforms electromagnetic fields to make an object invisible, but also acquires its properties automatically from its own elastic deformation. The demonstrated device is a ground-plane microwave cloak composed of an elastic metamaterial with a broad operational band (10-12 GHz) and nearly lossless electromagnetic properties. The metamaterial is uniform, or perfectly periodic, in its undeformed state and acquires the necessary gradient-index profile, mimicking a quasi-conformal transformation, naturally from a boundary load. This easy-to-fabricate hybrid elasto-electromagnetic metamaterial opens the door to implementations of a variety of transformation optics devices based on quasi-conformal maps.
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The possibility of making an optically large (many wavelengths in diameter) object appear invisible has been a subject of many recent studies. Exact invisibility scenarios for large (relative to the wavelength) objects involve (meta)materials with superluminal phase velocity [refractive index (RI) less than unity] and/or magnetic response. We introduce a new approximation applicable to certain device geometries in the eikonal limit: piecewise-uniform scaling of the RI. This transformation preserves the ray trajectories but leads to a uniform phase delay. We show how to take advantage of phase delays to achieve a limited (directional and wavelength-dependent) form of invisibility that does not require loss-ridden (meta)materials with superluminal phase velocities.
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We show that a quasi-two dimensional condensate of optically active excitons emits coherent light even in the absence of population inversion. This allows an unambiguous and clear experimental detection of the condensed phase. We prove that, due to the exciton–photon coupling, quantum and thermal fluctuations do not destroy condensation at finite temperature. Suitable conditions to achieve condensation are temperatures of a few K for typical exciton densities and the use of a pulsed and preferably circularly polarized, laser.
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We discuss light–heavy hole beats observed in transient optical experiments in GaAs quantum wells in terms of a free-boson coherent state model. This approach is compared with descriptions based on few-level representations. Results lead to an interpretation of the beats as due to classical electromagnetic interference. The boson picture correctly describes photon excitation of extended states and accounts for experiments involving coherent control of the exciton density and Rayleigh scattering beating.
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pt. 1. The effect of ideal limiting on signals and on noise.--pt. 2. The operation of an ideal limiter on signals imbedded in noise.
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"November 1995."
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Mode of access: Internet.