4,435 research outputs found

    Medical Library Association Historical Marker to be Installed in Philadelphia

    Get PDF
    During 2015, its 117th anniversary year, MLA will celebrate a novel and permanent way of informing both residents and visitors to Philadelphia about the association. Several months ago, the Pennsylvania Historical and Museum Commission voted to approve the nomination of an official State Historical Marker to commemorate MLA\u27s founding in Philadelphia in 1898. The text of the marker will not be revealed until the marker\u27s dedication ceremony in keeping with the commission\u27s guidelines

    Theoretical Parametric Study of the Relative Advantages of Winglets and Wing-Tip Extensions

    Get PDF
    For identical increases in bending moment, a winglet provides a greater gain in induced efficiency than tip extension. Winglet toe angle allows design trades between efficiency and root moment. A winglet shows the greatest benefit when the wing loads are heavy near the tip. Washout diminishes the benefit of either tip modification, and the gain in induced efficiency becomes a function of lift coefficient; thus, heavy wing loadings obtain the greatest benefit from a winglet, and low-speed performance is enhanced even more than cruise performance. Both induced efficiency and bending moment increase with winglet length and outward cant. The benefit of a winglet relative to a tip extension is greatest for a nearly vertical winglet. Root bending moment is proportional to the minimum weight of bending material required in the wing; thus, it is a valid index of the impact of tip modifications on a new wing design

    On the number of representations providing noiseless subsystems

    Full text link
    This paper studies the combinatoric structure of the set of all representations, up to equivalence, of a finite-dimensional semisimple Lie algebra. This has intrinsic interest as a previously unsolved problem in representation theory, and also has applications to the understanding of quantum decoherence. We prove that for Hilbert spaces of sufficiently high dimension, decoherence-free subspaces exist for almost all representations of the error algebra. For decoherence-free subsystems, we plot the function fd(n)f_d(n) which is the fraction of all dd-dimensional quantum systems which preserve nn bits of information through DF subsystems, and note that this function fits an inverse beta distribution. The mathematical tools which arise include techniques from classical number theory.Comment: 17 pp, 4 figs, accepted for Physical Review

    Integral Grothendieck-Riemann-Roch theorem

    Full text link
    We show that, in characteristic zero, the obvious integral version of the Grothendieck-Riemann-Roch formula obtained by clearing the denominators of the Todd and Chern characters is true (without having to divide the Chow groups by their torsion subgroups). The proof introduces an alternative to Grothendieck's strategy: we use resolution of singularities and the weak factorization theorem for birational maps.Comment: 24 page
    corecore