1,902 research outputs found

    Wide-bandwidth, tunable, multiple-pulse-width optical delays using slow light in cesium vapor

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    We demonstrate an all-optical delay line in hot cesium vapor that tunably delays 275 ps input pulses up to 6.8 ns and 740 input ps pulses up to 59 ns (group index of approximately 200) with little pulse distortion. The delay is made tunable with a fast reconfiguration time (hundreds of ns) by optically pumping out of the atomic ground states.Comment: 4 pages, 6 figure

    Finite Size Effects in Quark-Gluon Plasma Formation

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    Using lattice simulations of quenched QCD we estimate the finite size effects present when a gluon plasma equilibrates in a slab geometry, i.e., finite width but large transverse dimensions. Significant differences are observed in the free energy density for the slab when compared with bulk behavior. A small shift in the critical temperature is also seen. The free energy required to liberate heavy quarks relative to bulk is measured using Polyakov loops; the additional free energy required is on the order of 30−40MeV30-40 MeV at 2−3Tc2-3 T_c.Comment: LATTICE98(hightemp), talk at Lattice 98, 3 pages, 3 encapsulated postscript figures, uses espcrc2.st

    Landau-Ginsberg Theory of Quark Confinement

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    We describe the SU(3) deconfinement transition using Landau-Ginsberg theory. Drawing on perturbation theory and symmetry principles, we construct the free energy as a function of temperature and the Polyakov loop. Once the two adjustable parameters of the model are fixed, the pressure p, energy epsilon and Polyakov loop expectation value P_F are calculable functions of temperature. An excellent fit to the continuum extrapolation of lattice thermodynamics data can be achieved. In an extended form of the model, the glueball potential is responsible for breaking scale invariance at low temperatures. Three parameters are required, but the glueball mass and the gluon condensate are calculable functions of temperature, along with p, epsilon and P_F.Comment: Lattice99(Finite Temperature and Density) <= added keywords only change in revised version, sorry; 3 pages, LaTeX with espcrc2.sty and epsf.tex. Talk presented at Lattice99, Pisa, 29 June - 3 July 1999, to appear in Nucl. Phys. B (Proc.Suppl.

    Momentum and Heat Transfer in a Laminar Boundary Layer with Slip Flow

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    Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/77059/1/AIAA-22968-756.pd

    Perturbative Thermodynamics of Lattice QCD with Chiral-Invariant Four-Fermion Interactions

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    Lattice QCD with additional chiral-invariant four-fermion interactions is studied at nonzero temperature. Staggered Kogut-Susskind quarks are used. The four-fermion interactions are implemented by introducing bosonic auxiliary fields. A mean field treatment of the auxiliary fields is used to calculate the model's asymptotic scale parameter and perturbative thermodynamics, including the one-loop gluonic contributions to the energy, entropy, and pressure. In this approach the calculations reduce to those of ordinary lattice QCD with massive quarks. Hence, the previous calculations of these quantities in lattice QCD using massless quarks are generalized to the massive case.Comment: 22 pages, RevTeX, 8 EPS figures, uses epsf.sty and feynmf.st

    Relations Among Correlation Functions in the High Temperature Phase of QCD with Broken SU(3)

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    Group-theoretic arguments are used to determine the dependence of two-point correlators of quark bilinears on the current quark masses. The leading difference between π\pi and δ\delta correlators is found to be of order msm_s times a U(1)A_{\scriptscriptstyle A}-violating correlator. These general arguments are consistent with Schaefer's observation that if U(1)A_{\scriptscriptstyle A} violation persists to high enough temperatures then the strange η\eta can be lighter than the non-strange one.Comment: 8 page

    Exploring the Social Impacts of a Summer Camp for Youth With Tourette Syndrome

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    Although a wealth of research exists documenting the positive social outcomes promoted by summer camps, research specifically examining youths with Tourette Syndrome (TS) within the camp context is lacking. This study utilized a phenomenological approach to explore the social impacts of a weeklong camp specifically for youths with TS, involving focus groups with 18 campers aged 10–16, interviews with 10 staff members, and participant observations compiled by the researcher. Multiple themes and sub-themes concerning the social impacts of the camp experience were identified, including (a) relatedness (not alone and self-assurance); (b) social development (friendships, optimism, educational experience, and bullying); (c) programmatic outcomes (unique program opportunities and cabin bonding); and (d) various implications for professional practice and future research are discussed
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