1,645 research outputs found

    Inflationary Models Driven by Adiabatic Matter Creation

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    The flat inflationary dust universe with matter creation proposed by Prigogine and coworkers is generalized and its dynamical properties are reexamined. It is shown that the starting point of these models depends critically on a dimensionless parameter Σ\Sigma, closely related to the matter creation rate ψ\psi. For Σ\Sigma bigger or smaller than unity flat universes can emerge, respectively, either like a Big-Bang FRW singularity or as a Minkowski space-time at t=−∞t=-\infty. The case Σ=1\Sigma=1 corresponds to a de Sitter-type solution, a fixed point in the phase diagram of the system, supported by the matter creation process. The curvature effects have also been investigated. The inflating de Sitter is a universal attractor for all expanding solutions regardless of the initial conditions as well as of the curvature parameter.Comment: 25 pages, 2 figures(available from the authors), uses LATE

    Universal Irreversibility of Normal Quantum Diffusion

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    Time-reversibility measured by the deviation of the perturbed time-reversed motion from the unperturbed one is examined for normal quantum diffusion exhibited by four classes of quantum maps with contrastive physical nature. Irrespective of the systems, there exist a universal minimal quantum threshold above which the system completely loses the past memory, and the time-reversed dynamics as well as the time-reversal characteristics asymptotically trace universal curves independent of the details of the systems.Comment: 4 pages, 4 figure

    Thermodynamic Field Theory with the Iso-Entropic Formalism

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    A new formulation of the thermodynamic field theory (TFT) is presented. In this new version, one of the basic restriction in the old theory, namely a closed-form solution for the thermodynamic field strength, has been removed. In addition, the general covariance principle is replaced by Prigogine's thermodynamic covariance principle (TCP). The introduction of TCP required the application of an appropriate mathematical formalism, which has been referred to as the iso-entropic formalism. The validity of the Glansdorff-Prigogine Universal Criterion of Evolution, via geometrical arguments, is proven. A new set of thermodynamic field equations, able to determine the nonlinear corrections to the linear ("Onsager") transport coefficients, is also derived. The geometry of the thermodynamic space is non-Riemannian tending to be Riemannian for hight values of the entropy production. In this limit, we obtain again the same thermodynamic field equations found by the old theory. Applications of the theory, such as transport in magnetically confined plasmas, materials submitted to temperature and electric potential gradients or to unimolecular triangular chemical reactions can be found at references cited herein.Comment: 35 page

    Slow, Steady-State Transport with "Loading" and Bulk Reactions: the Mixed Ionic Conductor La2_2CuO4+δ_{4+\delta}

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    We consider slow, steady transport for the normal state of the superconductor La2_2CuO4+δ_{4+\delta} in a one-dimensional geometry, with surface fluxes sufficiently general to permit oxygen to be driven into the sample (``loaded'') either by electrochemical means or by high oxygen partial pressure. We include the bulk reaction O→\toO2−+2h^{2-}+2h, where neutral atoms (aa) go into ions (ii) and holes (hh). For slow, steady transport, the transport equations simplify because the bulk reaction rate density rr and the bulk loading rates ∂tn\partial_t n then are uniform in space and time. All three fluxes jj must be specified at each surface, which for a uniform current density JJ corresponds to five independent fluxes. These fluxes generate two types of static modes at each surface and a bulk response with a voltage profile that varies quadratically in space, characterized by JJ and the total oxygen flux jOj_O (neutral plus ion) at each surface. One type of surface mode is associated with electrical screening; the other type is associated both with diffusion and drift, and with chemical reaction (the {\it diffusion-reaction mode}). The diffusion-reaction mode is accompanied by changes in the chemical potentials μ\mu, and by reactions and fluxes, but it neither carries current (J=0) nor loads the system chemically (jO=0j_O=0). Generation of the diffusion-reaction mode may explain the phenomenon of ``turbulence in the voltage'' often observed near the electrodes of other mixed ionic electronic conductors (MIECs).Comment: 11 pages, 1 figur

    Time-reversal symmetric resolution of unity without background integrals in open quantum systems

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    We present a new complete set of states for a class of open quantum systems, to be used in expansion of the Green's function and the time-evolution operator. A remarkable feature of the complete set is that it observes time-reversal symmetry in the sense that it contains decaying states (resonant states) and growing states (anti-resonant states) parallelly. We can thereby pinpoint the occurrence of the breaking of time-reversal symmetry at the choice of whether we solve Schroedinger equation as an initial-condition problem or a terminal-condition problem. Another feature of the complete set is that in the subspace of the central scattering area of the system, it consists of contributions of all states with point spectra but does not contain any background integrals. In computing the time evolution, we can clearly see contribution of which point spectrum produces which time dependence. In the whole infinite state space, the complete set does contain an integral but it is over unperturbed eigenstates of the environmental area of the system and hence can be calculated analytically. We demonstrate the usefulness of the complete set by computing explicitly the survival probability and the escaping probability as well as the dynamics of wave packets. The origin of each term of matrix elements is clear in our formulation, particularly the exponential decays due to the resonance poles.Comment: 62 pages, 13 figure

    Emergence of Spacetime

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    Starting from a background Zero Point Field (or Dark Energy) we show how an array of oscillators at the Planck scale leads to the formation of elementary particles and spacetime and also to a cosmology consistent with latest observations.Comment: Latex, 39 page

    Consistent thermodynamics for spin echoes

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    Spin-echo experiments are often said to constitute an instant of anti-thermodynamic behavior in a concrete physical system that violates the second law of thermodynamics. We argue that a proper thermodynamic treatment of the effect should take into account the correlations between the spin and translational degrees of freedom of the molecules. To this end, we construct an entropy functional using Boltzmann macrostates that incorporates both spin and translational degrees of freedom. With this definition there is nothing special in the thermodynamics of spin echoes: dephasing corresponds to Hamiltonian evolution and leaves the entropy unchanged; dissipation increases the entropy. In particular, there is no phase of entropy decrease in the echo. We also discuss the definition of macrostates from the underlying quantum theory and we show that the decay of net magnetization provides a faithful measure of entropy change.Comment: 15 pages, 2 figs. Changed figures, version to appear in PR

    INTRINSIC MECHANISM FOR ENTROPY CHANGE IN CLASSICAL AND QUANTUM EVOLUTION

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    It is shown that the existence of a time operator in the Liouville space representation of both classical and quantum evolution provides a mechanism for effective entropy change of physical states. In particular, an initially effectively pure state can evolve under the usual unitary evolution to an effectively mixed state.Comment: 20 pages. For more information or comments contact E. Eisenberg at [email protected] (internet)

    Irreversible thermodynamics of open chemical networks I: Emergent cycles and broken conservation laws

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    In this and a companion paper we outline a general framework for the thermodynamic description of open chemical reaction networks, with special regard to metabolic networks regulating cellular physiology and biochemical functions. We first introduce closed networks "in a box", whose thermodynamics is subjected to strict physical constraints: the mass-action law, elementarity of processes, and detailed balance. We further digress on the role of solvents and on the seemingly unacknowledged property of network independence of free energy landscapes. We then open the system by assuming that the concentrations of certain substrate species (the chemostats) are fixed, whether because promptly regulated by the environment via contact with reservoirs, or because nearly constant in a time window. As a result, the system is driven out of equilibrium. A rich algebraic and topological structure ensues in the network of internal species: Emergent irreversible cycles are associated to nonvanishing affinities, whose symmetries are dictated by the breakage of conservation laws. These central results are resumed in the relation a+b=sYa + b = s^Y between the number of fundamental affinities aa, that of broken conservation laws bb and the number of chemostats sYs^Y. We decompose the steady state entropy production rate in terms of fundamental fluxes and affinities in the spirit of Schnakenberg's theory of network thermodynamics, paving the way for the forthcoming treatment of the linear regime, of efficiency and tight coupling, of free energy transduction and of thermodynamic constraints for network reconstruction.Comment: 18 page

    Fluctuation theorem for the effusion of an ideal gas

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    The probability distribution of the entropy production for the effusion of an ideal gas between two compartments is calculated explicitly. The fluctuation theorem is verified. The analytic results are in good agreement with numerical data from hard disk molecular dynamics simulations.Comment: 11 pages, 10 figures, 2 table
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