Static feed water electrolysis subsystem development

This disclosure is directed to an electrolysis cell forming hydrogen and oxygen at spaced terminals. The anode terminal is porous and able to form oxygen within the cell and permit escape of the gaseous oxygen through the anode and out through a flow line in the presence of backpressure. Hydrogen is liberated in the cell at the opposing solid metal cathode which is permeable to hydrogen but not oxygen so that the migratory hydrogen formed in the cell is able to escape from the cell. The cell is maintained at an elevated pressure so that oxygen liberated by the cell is delivered at elevated pressure without pumping to raise the pressure of the oxygen

On chaos in mean field spin glasses

We study the correlations between two equilibrium states of SK spin glasses at different temperatures or magnetic fields. The question, presiously investigated by Kondor and Kondor and V\'egs\"o, is approached here constraining two copies of the same system at different external parameters to have a fixed overlap. We find that imposing an overlap different from the minimal one implies an extensive cost in free energy. This confirms by a different method the Kondor's finding that equilibrium states corresponding to different values of the external parameters are completely uncorrelated. We also consider the Generalized Random Energy Model of Derrida as an example of system with strong correlations among states at different temperatures.Comment: 19 pages, Late

TDC Chip and Readout Driver Developments for COMPASS and LHC-Experiments

A new TDC-chip is under development for the COMPASS experiment at CERN. The ASIC, which exploits the 0.6 micrometer CMOS sea-of-gate technology, will allow high resolution time measurements with digitization of 75 ps, and an unprecedented degree of flexibility accompanied by high rate capability and low power consumption. Preliminary specifications of this new TDC chip are presented. Furthermore a FPGA based readout-driver and buffer-module as an interface between the front-end of the COMPASS detector systems and an optical S-LINK is in development. The same module serves also as remote fan-out for the COMPASS trigger distribution and time synchronization system. This readout-driver monitors the trigger and data flow to and from front-ends. In addition, a specific data buffer structure and sophisticated data flow control is used to pursue local pre-event building. At start-up the module controls all necessary front-end initializations.Comment: 5 pages, 4 figure

Glassy Mean-Field Dynamics of the Backgammon model

In this paper we present an exact study of the relaxation dynamics of the backgammon model. This is a model of a gas of particles in a discrete space which presents glassy phenomena as a result of {\it entropy barriers} in configuration space. The model is simple enough to allow for a complete analytical treatment of the dynamics in infinite dimensions. We first derive a closed equation describing the evolution of the occupation number probabilities, then we generalize the analysis to the study the autocorrelation function. We also consider possible variants of the model which allow to study the effect of energy barriers.Comment: 21 pages, revtex, 4 uuencoded figure

Algebraic Fermi liquid from phase fluctuations: "topological" fermions, vortex "berryons" and QED3 theory of cuprate superconductors

Within the phase fluctuation model for the pseudogap state of cuprate superconductors we identify a novel statistical "Berry phase" interaction between the nodal quasiparticles and fluctuating vortices. The effective action describing this model assumes the form of an anisotropic Euclidean quantum electrodynamics in (2+1) dimensions (QED_3) and naturally generates the marginal Fermi liquid behavior for its fermionic excitations. The doping axis in the x-T phase diagram emerges as a quantum critical line which regulates low energy fermiology. We examine the merits of our theory in light of available experiments.Comment: 5 pages REVTeX + 2 PostScript Figures. Final version to appear in PR

Temperature evolution and bifurcations of metastable states in mean-field spin glasses, with connections with structural glasses

The correlations of the free-energy landscape of mean-field spin glasses at different temperatures are investigated, concentrating on models with a first order freezing transition. Using a ``potential function'' we follow the metastable states of the model in temperature, and discuss the possibility of level crossing (which we do not find) and multifurcation (which we find). The dynamics at a given temperature starting from an equilibrium configuration at a different temperature is also discussed. In presence of multifurcation, we find that the equilibrium is never achieved, leading to aging behaviour at slower energy levels than usual aging. The relevance of the observed mechanisms for real structural glasses is discussed, and some numerical simulations of a soft sphere model of glass are presented.Comment: 16 pages, LaTeX, 10 figures (12 postscript files

Nonequilibrium dynamics of a simple stochastic model

We investigate the low-temperature dynamics of a simple stochastic model, introduced recently in the context of the physics of glasses. The slowest characteristic time at equilibrium diverges exponentially at low temperature. On smaller time scales, the nonequilibrium dynamics of the system exhibits an aging regime. We present an analytical study of the scaling behaviour of the mean energy, of its local correlation and response functions, and of the associated fluctuation-dissipation ratio throughout the regime of low temperature and long times. This analysis includes the aging regime, the convergence to equilibrium, and the crossover behaviour between them.Comment: 36 pages, plain tex, 7 figures, to be published by Journal of Physics

Effective "Penetration Depth" in the Vortex State of a d-wave Superconductor

The temperature and field dependence of the effective magnetic penetration depth in the vortex state of a d-wave superconductor, as measured by muon spin rotation experiments, is calculated using a nonlocal London model. We show that at temperatures below T^* \propto \sqrt{B}, the linear T-dependence of the effective penetration depth crosses over to a T^3-dependence. This could provide an explanation for the low temperature flattening of the effective penetration depth curves observed in a recent muon spin rotation experiment.Comment: 4 pages, RevTex, 3 Postscript figure

White-crowned sparrows tutored with syllable pairs can produce full songs

Journal ArticleDuring their 'sensitive period', young songbirds develop an 'acquired template', representing a memory of the song(s) that it hears. Later, during the sensorimotor phase, birds use this template to evaluate, via auditory feedback, their vocalizations