2,043 research outputs found

    An experimental study of the effects of army recruitment television advertising on high school seniors

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    In order for Army recruiters in the Appalachian region to effectively reach their target audience through television advertising, they must know which segment within the overall stated target audience of high school seniors between the ages of 17 to 21 are most likely to be influenced by Army recruitment advertising. Recruiters must also determine the type of programming preferred by the primary target segment to enable recruiting messages to be placed in programming where it is likely to have the most impact and achieve maximum frequency of exposure among the most receptive audience

    Occurrence of the Phoronid Phoronopsis albomaculata in Cocos Island, Costa Rica.

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    v. ill. 23 cm.QuarterlyThe phoronid Phoronopsis albomaculata was collected in subtidal (28– 35 m) sandy sediments in Bahı´a Chatham during a benthic survey designed to describe the biota of Cocos Island (Isla del Coco), Costa Rica, a national park and Human Heritage Site. Occurrence of this widespread species in Cocos Island is the first report of a phoronid for Costa Rican waters and is the second locality recorded for the eastern Pacific. Taxonomically significant characters (presence of an epidermal collar, extent of coiling of lophophore and nephridia) are discussed. Comparisons are made between depth and abundance of this species from Cocos Island and results of previous studies

    Perturbation theory for the effective diffusion constant in a medium of random scatterer

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    We develop perturbation theory and physically motivated resummations of the perturbation theory for the problem of a tracer particle diffusing in a random media. The random media contains point scatterers of density ρ\rho uniformly distributed through out the material. The tracer is a Langevin particle subjected to the quenched random force generated by the scatterers. Via our perturbative analysis we determine when the random potential can be approximated by a Gaussian random potential. We also develop a self-similar renormalisation group approach based on thinning out the scatterers, this scheme is similar to that used with success for diffusion in Gaussian random potentials and agrees with known exact results. To assess the accuracy of this approximation scheme its predictions are confronted with results obtained by numerical simulation.Comment: 22 pages, 6 figures, IOP (J. Phys. A. style