93,718 research outputs found

    Thermodynamics of D-brane Probes

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    We discuss the dynamics and thermodynamics of particle and D-brane probes moving in non-extremal black hole/brane backgrounds. When a probe falls from asymptotic infinity to the horizon, it transforms its potential energy into heat, TdSTdS, which is absorbed by the black hole in a way consistent with the first law of thermodynamics. We show that the same remains true in the near-horizon limit, for BPS probes only, with the BPS probe moving from AdS infinity to the horizon. This is a quantitative indication that the brane-probe reaching the horizon corresponds to thermalization in gauge theory. It is shown that this relation provides a way to reliably compute the entropy away from the extremal limit (towards the Schwarzschild limit).Comment: 12 pages; Based on talks presented at the midterm meeting of the TMR network "Physics beyond the standard model," held in Trieste in March 1999, and at the 1998 Corfu Summer Institute on Elementary Particle Physic

    String loop corrections to gauge and Yukawa couplings

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    We report on the recent progress in computing the effective supergravity action from superstring scattering amplitudes beyond the tree approximation. We discuss the moduli-dependent string loop corrections to gauge, gravitational and Yukawa couplings.Comment: 11 pages, CPTH-C218.0193 (Based on talks presented at the Rome Workshop STRINGS 92, at the 7th Meeting of the American Physical Society, and at the 26th Erice Workshop: ``From Superstrings to Supergravity"

    Duality of N=2 Heterotic -- Type I Compactifications in Four Dimensions

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    We discuss type I -- heterotic duality in four-dimensional models obtained as a Coulomb phase of the six-dimensional U(16) orientifold model compactified on T^2 with arbitrary SU(16) Wilson lines. We show that Kahler potentials, gauge threshold corrections and the infinite tower of higher derivative F-terms agree in the limit that corresponds to weak coupling, large T^2 heterotic compactifications. On the type I side, all these quantities are completely determined by the spectrum of N=2 BPS states that originate from D=6 massless superstring modes.Comment: 22 pages, LaTeX; typos corrected and references adde

    Cost effectiveness of conventional versus LANDSAT use data for hydrologic modeling

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    Six case studies were analyzed to investigate the cost effectiveness of using land use data obtained from LANDSAT as opposed to conventionally obtained data. A procedure was developed to determine the relative effectiveness of the two alternative means of acquiring data for hydrological modelling. The cost of conventionally acquired data ranged between 3,000and3,000 and 16,000 for the six test basins. Information based on LANDSAT imagery cost between 2,000and2,000 and 5,000. Results of the effectiveness analysis shows the differences between the two methods are insignificant. From the cost comparison and the act that each method, conventional and LANDSAT, is shown to be equally effective in developing land use data for hydrologic studies, the cost effectiveness of the conventional or LANDSAT method is found to be a function of basin size for the six test watersheds analyzed. The LANDSAT approach is cost effective for areas containing more than 10 square miles

    Distributed supply chain simulation in GRIDS

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    Amongst the majority of work done in supply chain simulation, papers have emerged that examine the area of model distribution. The executions of simulations on distributed hosts as a coupled model require both coordination and facilitating infrastructure. A distributed environment, the Generic Runtime Infrastructure for Distributed Simulation (GRIDS) is suggested to provide the bonding requirements for such a model. The advantages of transparently connecting the distributed components of a supply chain simulation allow the construction of a conceptual simulation while releasing the modeler from the complexities of the underlying network. The infrastructure presented demonstrates scalability without losing flexibility for future extensions based on open industry standard
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