Transport coefficients from the lattice?

The prospects of extracting transport coefficients from euclidean lattice simulations are discussed. Some general comments on the reconstruction of spectral functions using the Maximal Entropy Method are given as well.Comment: Lattice2002(nonzerot), 3 pages with 2 eps figure

Transport coefficients and the 2PI effective action in the large N limit

We discuss the computation of transport coefficients in large N_f QCD and the O(N) model for massive particles. The calculation is organized using the 1/N expansion of the 2PI effective action to next-to-leading order. For the gauge theory, we verify gauge fixing independence and consistency with the Ward identity. In the gauge theory, we find a nontrivial dependence on the fermion mass.Comment: 10 pages, based on presentations at Strong and Electroweak Matter (SEWM04), Helsinki, Finland, June 16-19 2004, and the Workshop on QCD in Extreme Environments, Argonne National Laboratory, USA, June 29-July 3 200

Transport coefficients and quantum fields

Various aspects of transport coefficients in quantum field theory are reviewed. We describe recent progress in the calculation of transport coefficients in hot gauge theories using Kubo formulas, paying attention to the fulfillment of Ward identities. We comment on why the color conductivity in hot QCD is much simpler to compute than the electrical conductivity. The nonperturbative extraction of transport coefficients from lattice QCD calculations is briefly discussed.Comment: 15 pages with 9 eps figures. Combined invited talk by G.A. and poster by J.M.M.R. presented at Strong and Electroweak Matter (SEWM 2002), Heidelberg, Germany, 2-5 Oct 200

3D high definition video coding on a GPU-based heterogeneous system

H.264/MVC is a standard for supporting the sensation of 3D, based on coding from 2 (stereo) to N views. H.264/MVC adopts many coding options inherited from single view H.264/AVC, and thus its complexity is even higher, mainly because the number of processing views is higher. In this manuscript, we aim at an efficient parallelization of the most computationally intensive video encoding module for stereo sequences. In particular, inter prediction and its collaborative execution on a heterogeneous platform. The proposal is based on an efficient dynamic load balancing algorithm and on breaking encoding dependencies. Experimental results demonstrate the proposed algorithm's ability to reduce the encoding time for different stereo high definition sequences. Speed-up values of up to 90× were obtained when compared with the reference encoder on the same platform. Moreover, the proposed algorithm also provides a more energy-efficient approach and hence requires less energy than the sequential reference algorith

Optical Absorption Spectra of Ag11 Isomers by First-Principles Theoretical Spectroscopy with Time-dependent Density Functional Theory

The optical absorption spectrum of the three most stable isomers of the Ag11 system was calculated using the time-dependent density functional theory, with the generalized gradient approximation for the exchange and correlation potential, and a relativistic pseudopotential parametrization for the modelling of the ion-electron interaction. The computational scheme is based on a real space code, where the photoabsorption spectrum is calculated by using the formalism developed by Casida. The significantly different spectra of the three isomers permit the identification of the ground-state configuration predominantly present in the laboratory beams in base to a comparison between the calculated photoabsorption spectrum of the most stable configuration of Ag11 and the measured spectra of medium-size silver clusters trapped in noble gas Ar and Ne matrices at different temperatures. This assignment is confirmed by the fact that this isomer has the lowest calculated energy.Comment: 6 pages, 3 color figures, submitted to Chem. Phys. Let

Trees of Irreducible Numerical Semigroups

A 2011 paper by Blanco and Rosales describes an algorithm for constructing a directed tree graph of irreducible numerical semigroups of fixed Frobenius numbers. This paper will provide an overview of irreducible numerical semigroups and the directed tree graphs. We will also present new findings and conjectures concerning the structure of these trees