28,307 research outputs found

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    Implications of Saito's coronal density model on the polar solar wind flow and heavy ion abundances

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    A comparison of polar solar wind proton flux upper limits derived using a coronal density model, with Lyman alpha measurements of the length of the neutral H tail of comet Bennet at high latitudes, shows that either extended heating beyond 2 solar radii is necessary some of the time or that the model's polar densities are too low. Whichever possibility is the case, the fact that the solar wind particle flux does not appear to decrease with increasing latitude indicates that the heavy element content of the high latitude wind may be similar to that observed in the ecliptic. It was then shown that solar wind heavy ion observations at high latitudes allow a determination of the electron temperature at heights which bracket the nominal location of the coronal temperature maximum thus providing information concerning the magnitude and extent of mechanical dissipation in the intermediate corona

    Preparation of silver-activated zinc sulfide thin films

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    Silver improves luminescence and reduces contamination of zinc sulfide phosphors. The silver is added after the zinc sulfide phosphors are deposited in thin films by vapor evaporation, but before calcining, by immersion in a solution of silver salt

    Continuity and Discontinuity of the Boundary Layer Tail

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    We investigate the continuity properties of the homogenized boundary data g\overline{g} for oscillating Dirichlet boundary data problems. We show that, for a generic non-rotation-invariant operator and boundary data, g\overline{g} is discontinuous at every rational direction. In particular this implies that the continuity condition of Choi and Kim is essentially sharp. On the other hand, when this condition holds, we show a H\"{o}lder modulus of continuity for g\overline{g}. When the operator is linear we show that g\overline{g} is H\"{o}lder-1d\frac{1}{d} up to a logarithmic factor. The proofs are based on a new geometric observation on the limiting behavior of g\overline{g} at rational directions, reducing to a class of two dimensional problems for projections of the homogenized operator.Comment: 36 pages, 1 figure. Version to appear in Annales scientifiques de l'EN

    IUE observations of periodic comets Tempel-2, Kopff, and Tempel-1

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    We summarize the results of observations made between 10 Jun. - 18 Dec. 1988 with the International Ultraviolet Explorer (IUS) of comet P/Tempel-2 during its 1988 appearance. The derived water production rate and relative gas/dust ratio are compared with those of P/Halley, observed with IUE in 1985-86, and other potential Comet Rendezvous/Asteroid Flyby (CRAF) target comets, P/Kopff and P/Tempel-1, both observed with IUE in 1983

    Sensitivity and pointing accuracy of the NEMO km3^3 telescope

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    n this paper we present the results of Monte Carlo simulation studies on the capability of the proposed NEMO km3 telescope to detect high energy neutrinos. We calculated the detector sensitivity to muon neutrinos coming from a generic point-like source. We also simulated the lack of atmospheric muons in correspondence to the Moon disk in order to determine the detector angular resolution and to check the absolute pointing capability.Comment: To be published on VLVNT2 proceedings (Catania, Italy, November 8-11, 2005

    Treatment of the background error in the statistical analysis of Poisson processes

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    The formalism that allows to take into account the error sigma_b of the expected mean background b in the statistical analysis of a Poisson process with the frequentistic method is presented. It is shown that the error sigma_b cannot be neglected if it is not much smaller than sqrt(b). The resulting confidence belt is larger that the one for sigma_b=0, leading to larger confidence intervals for the mean mu of signal events.Comment: 15 pages including 2 figures, RevTeX. Final version published in Phys. Rev. D 59 (1999) 11300

    Comment on "Including Systematic Uncertainties in Confidence Interval Construction for Poisson Statistics"

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    The incorporation of systematic uncertainties into confidence interval calculations has been addressed recently in a paper by Conrad et al. (Physical Review D 67 (2003) 012002). In their work, systematic uncertainities in detector efficiencies and background flux predictions were incorporated following the hybrid frequentist-Bayesian prescription of Cousins and Highland, but using the likelihood ratio ordering of Feldman and Cousins in order to produce "unified" confidence intervals. In general, the resulting intervals behaved as one would intuitively expect, i.e. increased with increasing uncertainties. However, it was noted that for numbers of observed events less than or of order of the expected background, the intervals could sometimes behave in a completely counter-intuitive fashion -- being seen to initially decrease in the face of increasing uncertainties, but only for the case of increasing signal efficiency uncertainty. In this comment, we show that the problematic behaviour is due to integration over the signal efficiency uncertainty while maximising the best fit alternative hypothesis likelihood. If the alternative hypothesis likelihood is determined by unconditionally maximising with respect to both the unknown signal and signal efficiency uncertainty, the limits display the correct intuitive behaviour.Comment: Submitted to Physical Review

    A Rigorous Proof of Fermi Liquid Behavior for Jellium Two-Dimensional Interacting Fermions

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    Using the method of continuous constructive renormalization group around the Fermi surface, it is proved that a jellium two-dimensional interacting system of Fermions at low temperature TT remains analytic in the coupling constant λ\lambda for λlogTK|\lambda| |\log T| \le K where KK is some numerical constant and TT is the temperature. Furthermore in that range of parameters, the first and second derivatives of the self-energy remain bounded, a behavior which is that of Fermi liquids and in particular excludes Luttinger liquid behavior. Our results prove also that in dimension two any transition temperature must be non-perturbative in the coupling constant, a result expected on physical grounds. The proof exploits the specific momentum conservation rules in two dimensions.Comment: 4 pages, no figure
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