522 research outputs found

    Chiral perturbation theory for the Wilson lattice action

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    We extend chiral perturbation theory to include linear dependence on the lattice spacing aa for the Wilson action. The perturbation theory is written as a double expansion in the small quark mass mqm_q and lattice spacing aa. We present formulae for the mass and decay constant of a flavor-non-singlet meson in this scheme to order aa and mq2m_q^2. The extension to the partially quenched theory is also described.Comment: 9 pages LaTeX2

    Partially Quenched QCD with Non-Degenerate Dynamical Quarks

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    We discuss the importance of using partially quenched theories with three degenerate quarks for extrapolating to QCD, and present some relevant results from chiral perturbation theory.Comment: LATTICE99 talk. 3 pages, 2 figures. Uses epsf and espcrc2.st

    Physical Results from Partially Quenched Simulation

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    We describe how one can use chiral perturbation theory to obtain results for physical quantities, such as quark masses, using partially quenched simulations.Comment: Written version of two talks at DPF 2000. 6 pages, 2 figure

    Genome-wide identification, expression and chromosomal location of the genes encoding chitinolytic enzymes in Zea mays

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    Chitinolytic enzymes are important pathogenesis and stress related proteins. We identified 27 putative genes encoding endochitinases in the maize genome via in silico techniques and four exochitinases. Only seven of the endochitinases and segments of the exochitinases were heretofore known. The endochitinases included members of family 19 chitinases (classes I-IV of PR3, II of PR4) and members of family 18 chitinases (class III of PR8). Some similar enzymes were detected on adjacent regions of the same chromosome, and seem to result from duplication events. Most of the genes expressed were identified from EST libraries from plants exposed to biotic or abiotic stresses but also from libraries from tissues not exposed to stresses. We isolated proteins from seedlings of maize in the presence or absence of the symbiotic root colonizing fungus Trichoderma harzianum strain T22, and analyzed the activity of chitinolytic enzymes using an in-gel activity assay. The activity bands were identified by LC/MS/MS using the database from our in silico study. The identities of the enzymes changed depending on whether or not T22 was present. One activity band of about 95kDa appeared to be a heterodimer between an exochitinase and any of several different endochitinases. The identity of the endochitinase component appeared to be dependent upon treatmen

    The effect of extreme confinement on the nonlinear-optical response of quantum wires

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    This work focuses on understanding the nonlinear-optical response of a 1-D quantum wire embedded in 2-D space when quantum-size effects in the transverse direction are minimized using an extremely weighted delta function potential. Our aim is to establish the fundamental basis for understanding the effect of geometry on the nonlinear-optical response of quantum loops that are formed into a network of quantum wires. Using the concept of leaky quantum wires, it is shown that in the limit of full confinement, the sum rules are obeyed when the transverse infinite-energy continuum states are included. While the continuum states associated with the transverse wavefunction do not contribute to the nonlinear optical response, they are essential to preserving the validity of the sum rules. This work is a building block for future studies of nonlinear-optical enhancement of quantum graphs (which include loops and bent wires) based on their geometry. These properties are important in quantum mechanical modeling of any response function of quantum-confined systems, including the nonlinear-optical response of any system in which there is confinement in at leat one dimension, such as nanowires, which provide confinement in two dimensions
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