546 research outputs found

    Payload/orbiter contamination control requirement study: Spacelab configuration contamination study

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    The assessment of the Spacelab carrier induced contaminant environment was continued, and the ability of Spacelab to meet established contamination control criteria for the space transportation system program was determined. The primary areas considered included: (1) updating, refining, and improving the Spacelab contamination computer model and contamination analysis methodology, (2) establishing the resulting adjusted induced environment predictions for comparison with the applicable criteria, (3) determining the Spacelab design and operational requirements necessary to meet the criteria, (4) conducting mission feasibility analyses of the combined Spacelab/Orbiter contaminant environment for specific proposed mission and payload mixes, and (5) establishing a preliminary Spacelab mission support plan as well as model interface requirements; A summary of those activities conducted to date with respect to the modelling, analysis, and predictions of the induced environment, including any modifications in approach or methodology utilized in the contamination assessment of the Spacelab carrier, was presented

    Descriptions and phylogeny of four limnephiloid caddisflies (Trichoptera) based on first instars

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    First instars from a representative species of each of the limnephiloid families Goeridae, Brachycentridae, Lepdostomatidae, and Uenoidae and the sericostomatoid family Sericostomatidae were reared, described, and illustrated

    The locality of the fourth root of staggered fermion determinant in the interacting case

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    The fourth root approximation in LQCD simulations with dynamical staggered fermions requires justification. We test its validity numerically in the interacting theory in a renormalization group framework.Comment: 6 pages, Talk presented at Lattice 2005 (Machines and Algorithms

    The QCD equation of state with asqtad staggered fermions

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    We report on our result for the equation of state (EOS) with a Symanzik improved gauge action and the asqtad improved staggered fermion action at Nt=4N_t=4 and 6. In our dynamical simulations with 2+1 flavors we use the inexact R algorithm and here we estimate the finite step-size systematic error on the EOS. Finally we discuss the non-zero chemical potential extension of the EOS and give some preliminary results.Comment: 7 pages, 6 figures, presented at Lattice2006(High Temperature and Density), to appear in Proceedings of Scienc

    The equation of state with nonzero chemical potential for 2+1 flavors

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    We present results for the QCD equation of state with nonzero chemical potential using the Taylor expansion method with terms up to sixth order in the expansion. Our calculations are performed on asqtad 2+1 quark flavor lattices at Nt=4N_t=4.Comment: Talk given at the XXV International Symposium on Lattice Field Theory, July 30-4 August 2007, Regensburg, German

    Update on the physics of light pseudoscalar mesons

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    We present an update of the MILC investigation of the properties of light pseudoscalar mesons using three flavors of improved staggered quarks. Results are presented for the π\pi and KK leptonic decay constants, the CKM matrix element VusV_{us}, the up, down and strange quark masses, and the coefficients of the O(p4)O(p^4) chiral lagrangian. We have new data for lattice spacing a≈0.15a \approx 0.15 fm with several values of the light quark mass down to one-tenth the strange quark mass, higher statistics for a≈0.09a \approx 0.09 fm with the light quark mass equal to one-tenth the strange quark mass, and initial results for our smallest lattice spacing, a≈0.06a \approx 0.06 fm with light quark mass two-fifths of the strange quark mass.Comment: 7 pages, 4 figures. To be published in Proceedings of Science (Lattice 2006) 163 (2006

    Baryon masses with improved staggered quarks

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    The MILC collaboration's simulations with improved staggered quarks are being extended with runs at a lattice spacing of 0.06 fm with quark masses down to one tenth the strange quark mass. We give a brief introduction to these new simulations and the determination of the lattice spacing. Then we combine these new runs with older results to study the masses of the nucleon and the Omega minus in the continuum and chiral limits.Comment: 7 pages, proceedings from Lattice 2007 conferenc

    The Equation of State for QCD with 2+1 Flavors of Quarks

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    We report results for the interaction measure, pressure and energy density for nonzero temperature QCD with 2+1 flavors of improved staggered quarks. In our simulations we use a Symanzik improved gauge action and the Asqtad O(a2)O(a^2) improved staggered quark action for lattices with temporal extent Nt=4N_t=4 and 6. The heavy quark mass msm_s is fixed at approximately the physical strange quark mass and the two degenerate light quarks have masses mud=0.1msm_{ud} =0.1m_s or 0.2ms0.2m_s. The calculation of the thermodynamic observables employs the integral method where energy density and pressure are obtained by integration over the interaction measure.Comment: 6 pages, 1 figure, 3 tables, contribution to the XXIIIrd International Symposium on Lattice Field Theory, 25-30 July 2005, Trinity College, Dublin, Irelan
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