Lattice constraints on the thermal photon rate

We estimate the photon production rate from an SU(3) plasma at temperatures of about 1.1Tc and 1.3Tc. Lattice results for the vector current correlator at spatial momenta k ~ (2-6)T are extrapolated to the continuum limit and analyzed with the help of a polynomial interpolation for the corresponding spectral function, which vanishes at zero frequency and matches to high-precision perturbative results at large invariant masses. For small invariant masses the interpolation is compared with the NLO weak-coupling result, hydrodynamics, and a holographic model. At vanishing invariant mass we extract the photon rate which for k \gsim 3T is found to be close to the NLO weak-coupling prediction. For k \lsim 2T uncertainties remain large but the photon rate is likely to fall below the NLO prediction, in accordance with the onset of a strongly interacting behaviour characteristic of the hydrodynamic regime.Comment: 20 pages. v2: clarifications adde

Large effect of a small bias field in liquid-crystal magnetic transitions

Most liquid crystals show low sensitivity to magnetic field. However, in this paper we show that a small bias magnetic field not only breaks the symmetry of the ground state, but also plays a crucial role in facilitating the reorientation induced by a large test magnetic field. In particular, a small bias field may alter significantly the strength of the test field needed to observe a given reorientation of the liquid crystal. Moreover, the bias field interacts with other symmetry breaking features of the cell, e.g., pretilt, to change also the qualitative features of the equilibrium state

Stress Tensor of Static Dipoles in strongly coupled N\cal{N}=4 Gauge Theory

In the context of the AdS/CFT correspondence we calculate the induced stress tensor of static dipoles (electric-electric and electric-magnetic) in a strongly coupled ${\cal N}=4$ SYM gauge theory, by solving the linearized Einstein equation with Maldecena string as a source. Analytic expressions are given for the far-field and a near-field close to one charge, and compared to what one has in weak coupling. The result can be compared to lattice results for QCD-like theories in a deconfined but strongly coupled regime

The Operation of Multiple Reservoir Systems

The purpose of this workshop was to discuss, compare and evaluate various methods of operating, and determining operating policies for multi-purpose, multiple reservoir systems. While total reservoir capacities are known, the allocation of various storage volume zones within the reservoirs to various purposes, such as water supply or flood control, may vary in time and be dependent on reservoir operating policy. In the guidelines for preparation of the papers included in this volume, it was stressed that discussion should cover reservoir operation for all possible hydrological situations, i.e., in periods of flood, normal flow, and drought conditions. The importance of procedures used to determine when an extreme situation (such as drought), begins and ends, was emphasized, especially with respect to possible changes in reservoir operation. The participants were requested to discuss how operating policies might differ, depending on whether the reservoirs are in series or are parallel. Also, they were requested to distinguish between operation of "large" over-year storage reservoirs and "small" within-year storage reservoirs. If short-term hydrological forecasting and real-time control models were to be used, the workshop discussion would consider how these could be used together with long-term operating policies. Some 30 participants from 13 countries presented 17 papers at the workshop, all of which are included in these proceedings. The first nine provide an overview of how multiple reservoir systems are operated in certain countries. The remaining papers report in more detail on diverse case studies and provide discussion of some specific issues related to the subject of the workshop

Effective potential for Polyakov loops from a center symmetric effective theory in three dimensions

We present lattice simulations of a center symmetric dimensionally reduced effective field theory for SU(2) Yang Mills which employ thermal Wilson lines and three-dimensional magnetic fields as fundamental degrees of freedom. The action is composed of a gauge invariant kinetic term, spatial gauge fields and a potential for the Wilson line which includes a "fuzzy" bag term to generate non-perturbative fluctuations. The effective potential for the Polyakov loop is extracted from the simulations including all modes of the loop as well as for cooled configuration where the hard modes have been averaged out. The former is found to exhibit a non-analytic contribution while the latter can be described by a mean-field like ansatz with quadratic and quartic terms, plus a Vandermonde potential which depends upon the location within the phase diagram.Comment: 10 pages, 22 figures, v2: published version (minor clarifications, update of reference list

Determination of Freeze-out Conditions from Lattice QCD Calculations

Freeze-out conditions in Heavy Ion Collisions are generally determined by comparing experimental results for ratios of particle yields with theoretical predictions based on applications of the Hadron Resonance Gas model. We discuss here how this model dependent determination of freeze-out parameters may eventually be replaced by theoretical predictions based on equilibrium QCD thermodynamics.Comment: presented at the International Conference "Critical Point and Onset of Deconfinement - CPOD 2011", Wuhan, November 7-11, 201

Lublin-Vistula Case Study

Making optimum use of the water resources is a task which long has engaged human effort and which has, in recent decades, been studied within the framework of the integrated regional development plans. The "integrated development" of a region means the orderly marshalling of all its resources to promote human welfare. It is evident, however, that the influence of development of a given region upon the rest of the national economy is in most of the cases considerable. Moreover, the investment needs of any development scheme are closely linked to the needs of the whole economy. These introductory comments are especially relevant to the water resources development schemes. It is now widely recognized that individual water projects -- whether single or multipurpose -- cannot as a rule be undertaken with optimum benefit for the people affected before there is at least the broad outline of a plan for the entire drainage area. Although this paper concentrates on the Lublin region, some thoughts are also given to the related problems in the upper portion of the Vistula Basin. Information concerning the entire basin is problem-oriented. A description of the basin and its water resources is presented in some of the earlier IIASA documents. The paper ends with the formulation of a proposal for the Water Resources Sub-Project to be implemented within the framework of the Lublin-Vistula Research Program

Strongly coupled plasma with electric and magnetic charges

A number of theoretical and lattice results lead us to believe that Quark-Gluon Plasma not too far from $T_c$ contains not only electrically charged quasiparticles -- quarks and gluons -- but magnetically charged ones -- monopoles and dyons -- as well. Although binary systems like charge-monopole and charge-dyon were considered in details before in both classical and quantum settings, it is the first study of coexisting electric and magnetic particles in many-body context. We perform Molecular Dynamics study of strongly coupled plasmas with $\sim 1000$ particles and different fraction of magnetic charges. Correlation functions and Kubo formulae lead to such transport properties as diffusion constant, shear viscosity and electric conductivity: we compare the first two with empirical data from RHIC experiments as well as results from AdS/CFT correspondence. We also study a number of collective excitations in these systems.Comment: 2nd version, 22 pages, 32 figures: two important new figures have been included to compare our results with RHIC experiments and AdS/CFT results; a few new references and comments are added as wel