2,989 research outputs found

    Magnetic induction plasma engine Final report

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    Wall interaction reduction in magnetic induction plasma accelerato

    Neurophysiological findings relevant to echolocation in marine animals

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    A review of echolocation mechanisms in marine mammals, chiefly porpoises, is given. Data cover peripheral auditory and central neurophysiological specializations favorable to the analysis of echolocating clicks and their echoes. Conclusions show (1) signals are received from 50 up to at least 135 kHz, (2) sound is received through the mandible skin, and (3) the midbrain sites are insensitive to low frequencies (below 6 kHz)

    GLM permutation - nonparametric inference for arbitrary general linear models

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    Introduction: Permutation methods are finding growing use in neuroimag- ing data analyses (e.g. randomise in FSL, SnPM in SPM, XBAMM/BAMM/CAMBA, etc). These methods provide ex- act control of false positives, make only weak assumptions, and allow nonstandard types of statistics (e.g. smoothed variance t- test). With fast and inexpensive computing, there would seem few reasons not to use nonparametric methods. A significant limitation of these methods, however, is the lack of flexibility with respect to the experimental design and nuisance variables. Each specific design dictates the type of exchange- ability of null data, and hence how to permute. Nuisance effects (e.g. age) render data non-exchangeable even when the effect of interest is null. Hence, even something as simple as ANCOVA has no exact permutation test. Recently there has been an active literature on approximate– but accurate–permutation tests for 2-variable regression, one effect of interest, one nuisance (see review by Anderson & Robinson [1]). Here we extend and evaluate these methods for use with an arbitrary General Linear Model (GLM)

    Are All Static Black Hole Solutions Spherically Symmetric?

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    The static black hole solutions to the Einstein-Maxwell equations are all spherically symmetric, as are many of the recently discovered black hole solutions in theories of gravity coupled to other forms of matter. However, counterexamples demonstrating that static black holes need not be spherically symmetric exist in theories, such as the standard electroweak model, with electrically charged massive vector fields. In such theories, a magnetically charged Reissner-Nordstrom solution with sufficiently small horizon radius is unstable against the development of a nonzero vector field outside the horizon. General arguments show that, for generic values of the magnetic charge, this field cannot be spherically symmetric. Explicit construction of the solution shows that it in fact has no rotational symmetry at all.Comment: 6 pages, plain TeX. Submitted to GRF Essay Competitio

    Deep Spectroscopy in the Field of 3C 212

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    We present the results of longslit and multiaperture spectroscopy of faint galaxies in the field of the z=1.049 quasar 3C212. We show that an apparently aligned optical feature beyond the NW radio lobe has a redshift z=0.928, and a similarly aligned feature just beyond the SE radio lobe has a redshift z=1.053, quite close to that of the quasar. While the NW optical component is extremely well aligned with the radio jet and has a morphology that is very similar to that of the radio lobe lying 3" interior to it, the fact that we find three other field galaxies with closely similar redshifts indicates that it is most likely a member of an intervening group rather than an unusual example of true alignment with the radio structure. In addition, we have found two galaxies (besides the one near the SE radio lobe) having redshifts close to that of 3C212. We have firm or probable redshifts for 66 out of 82 galaxies we have observed in this field. Comparison with the redshift distribution of faint field galaxies indicates that a large fraction of the remaining 16 galaxies are likely to be at redshifts >1.4. There are at least two low-redshift dwarf starburst galaxies showing low metal abundance and high ionization in our sample; such galaxies are likely to be relatively common in very faint samples, and, under certain conditions, they could be confused with high-redshift objects.Comment: 15 pages, 4 figures, one of which is a separate JPEG plate. To be published in the April 1998 issue of The Astronomical Journa

    Disinhibition of restraint : a comparison of the Restraint Scale and the Three Factor Eating Questionnaire

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    The Aphrodite of Arles

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