498 research outputs found

    Louis XVI’s Chapel during the French Revolution 1789-1792

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    Abstract — The close association of Christianity with the late Bourbon monarchy’s style of governance has often been interpreted as a burdensome legacy, which impacted greatly on the period preceding the French Revolution. In recent years, historians have referred to the ideological, juridical and intellectual assaults on the religious foundations of the French crown, throughout the eighteenth century, either as a process of ‘ desacralization ’ or as the religious origins of the French Revolution. This article, though inspired by this school of thought, takes a different approach by examining the less well-known ceremonial and ritual components of this form of kingship, with particular reference to the king’s chapel. Louis XVI’s ecclesiastical household was both the centre of royal patronage for the Gallican Church and the chief regulatory authority of the monarch’s personal religious devotion. Its actions, transformation and fate during the Revolution are instructive in two ways. First, its survival during the first three years of the revolutionary troubles highlights its fundamental and constraining influence over the French monarchy. Secondly, the gradual, though determined, effort to undermine the pact between throne and altar that it represented exemplifi es a lesser known aspect of the national deputies ’ anticlerical agenda

    Review. Shadows of Revolution

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    Comment on ``Deterministic equations of motion and phase ordering dynamics''

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    Zheng [Phys. Rev. E {\bf 61}, 153 (2000), cond-mat/9909324] claims that phase ordering dynamics in the microcanonical ϕ4\phi^4 model displays unusual scaling laws. We show here, performing more careful numerical investigations, that Zheng only observed transient dynamics mostly due to the corrections to scaling introduced by lattice effects, and that Ising-like (model A) phase ordering actually takes place at late times. Moreover, we argue that energy conservation manifests itself in different corrections to scaling.Comment: 5 pages, 4 figure

    Aging at Criticality in Model C Dynamics

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    We study the off-equilibrium two-point critical response and correlation functions for the relaxational dynamics with a coupling to a conserved density (Model C) of the O(N) vector model. They are determined in an \epsilon=4-d expansion for vanishing momentum. We briefly discuss their scaling behaviors and the associated scaling forms are determined up to first order in epsilon. The corresponding fluctuation-dissipation ratio has a non trivial large time limit in the aging regime and, up to one-loop order, it is the same as that of the Model A for the physically relevant case N=1. The comparison with predictions of local scale invariance is also discussed.Comment: 13 pages, 1 figur

    Hamiltonian dynamics of the two-dimensional lattice phi^4 model

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    The Hamiltonian dynamics of the classical ϕ4\phi^4 model on a two-dimensional square lattice is investigated by means of numerical simulations. The macroscopic observables are computed as time averages. The results clearly reveal the presence of the continuous phase transition at a finite energy density and are consistent both qualitatively and quantitatively with the predictions of equilibrium statistical mechanics. The Hamiltonian microscopic dynamics also exhibits critical slowing down close to the transition. Moreover, the relationship between chaos and the phase transition is considered, and interpreted in the light of a geometrization of dynamics.Comment: REVTeX, 24 pages with 20 PostScript figure

    Phase transitions as topology changes in configuration space: an exact result

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    The phase transition in the mean-field XY model is shown analytically to be related to a topological change in its configuration space. Such a topology change is completely described by means of Morse theory allowing a computation of the Euler characteristic--of suitable submanifolds of configuration space--which shows a sharp discontinuity at the phase transition point, also at finite N. The present analytic result provides, with previous work, a new key to a possible connection of topological changes in configuration space as the origin of phase transitions in a variety of systems.Comment: REVTeX file, 5 pages, 1 PostScript figur

    Generalized entropy and temperature in nuclear multifragmentation

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    In the framework of a 2D Vlasov model, we study the time evolution of the "coarse-grained" Generalized Entropy (GE) in a nuclear system which undergoes a multifragmentation (MF) phase transition. We investigate the GE both for the gas and the fragments (surface and bulk part respectively). We find that the formation of the surface causes the growth of the GE during the process of fragmentation. This quantity then characterizes the MF and confirms the crucial role of deterministic chaos in filling the new available phase-space: at variance with the exact time evolution, no entropy change is found when the linear response is applied. Numerical simulations were used also to extract information about final temperatures of the fragments. From a fitting of the momentum distribution with a Fermi-Dirac function we extract the temperature of the fragments at the end of the process. We calculate also the gas temperature by averaging over the available phase space. The latter is a few times larger than the former, indicating a gas not in equilibrium. Though the model is very schematic, this fact seems to be very general and could explain the discrepancy found in experimental data when using the slope of light particles spectra instead of the double ratio of isotope yields method in order to extract the nuclear caloric curve.Comment: 26 pages, 9 postscript figures included, Revtex, some figures and part of text changed, version accepted for publication in PR

    Symmetries of microcanonical entropy surfaces

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    Symmetry properties of the microcanonical entropy surface as a function of the energy and the order parameter are deduced from the invariance group of the Hamiltonian of the physical system. The consequences of these symmetries for the microcanonical order parameter in the high energy and in the low energy phases are investigated. In particular the breaking of the symmetry of the microcanonical entropy in the low energy regime is considered. The general statements are corroborated by investigations of various examples of classical spin systems.Comment: 15 pages, 5 figures include
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