3,698 research outputs found

    Possible Detection of Causality Violation in a Non-local Scalar Model

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    We consider the possibility that there may be causality violation detectable at higher energies. We take a scalar nonlocal theory containing a mass scale Λ\Lambda as a model example and make a preliminary study of how the causality violation can be observed. We show how to formulate an observable whose detection would signal causality violation. We study the range of energies (relative to Λ\Lambda) and couplings to which the observable can be used.Comment: Latex, 30 page

    Improving the Efficiency of an Ideal Heat Engine: The Quantum Afterburner

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    By using a laser and maser in tandem, it is possible to obtain laser action in the hot exhaust gases involved in heat engine operation. Such a "quantum afterburner" involves the internal quantum states of working gas atoms or molecules as well as the techniques of cavity quantum electrodynamics and is therefore in the domain of quantum thermodynamics. As an example, it is shown that Otto cycle engine performance can be improved beyond that of the "ideal" Otto heat engine.Comment: 5 pages, 3 figure

    Visibility diagrams and experimental stripe structure in the quantum Hall effect

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    We analyze various properties of the visibility diagrams that can be used in the context of modular symmetries and confront them to some recent experimental developments in the Quantum Hall Effect. We show that a suitable physical interpretation of the visibility diagrams which permits one to describe successfully the observed architecture of the Quantum Hall states gives rise naturally to a stripe structure reproducing some of the experimental features that have been observed in the study of the quantum fluctuations of the Hall conductance. Furthermore, we exhibit new properties of the visibility diagrams stemming from the structure of subgroups of the full modular group.Comment: 8 pages in plain TeX, 7 figures in a single postscript fil

    Diffeomorphism on Horizon as an Asymptotic Isometry of Schwarzschild Black Hole

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    It is argued that the diffeomorphism on the horizontal sphere can be regarded as a nontrivial asymptotic isometry of the Schwarzschild black hole. We propose a new boundary condition of asymptotic metrics near the horizon and show that the condition admits the local time-shift and diffeomorphism on the horizon as the asymptotic symmetry.Comment: 18 pages, no figures, corrected some typo

    Cognition-Enhancing Drugs: Can We Say No?

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    Normative analysis of cognition-enhancing drugs frequently weighs the liberty interests of drug users against egalitarian commitments to a level playing field. Yet those who would refuse to engage in neuroenhancement may well find their liberty to do so limited in a society where such drugs are widespread. To the extent that unvarnished emotional responses are world-disclosive, neurocosmetic practices also threaten to provide a form of faulty data to their users. This essay examines underappreciated liberty-based and epistemic rationales for regulating cognition-enhancing drugs

    The stability of the O(N) invariant fixed point in three dimensions

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    We study the stability of the O(N) fixed point in three dimensions under perturbations of the cubic type. We address this problem in the three cases N=2,3,4N=2,3,4 by using finite size scaling techniques and high precision Monte Carlo simulations. It is well know that there is a critical value 2<Nc<42<N_c<4 below which the O(N) fixed point is stable and above which the cubic fixed point becomes the stable one. While we cannot exclude that Nc<3N_c<3, as recently claimed by Kleinert and collaborators, our analysis strongly suggests that NcN_c coincides with 3.Comment: latex file of 18 pages plus three ps figure

    How Stands Collapse II

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    I review ten problems associated with the dynamical wave function collapse program, which were described in the first of these two papers. Five of these, the \textit{interaction, preferred basis, trigger, symmetry} and \textit{superluminal} problems, were discussed as resolved there. In this volume in honor of Abner Shimony, I discuss the five remaining problems, \textit{tails, conservation law, experimental, relativity, legitimization}. Particular emphasis is given to the tails problem, first raised by Abner. The discussion of legitimization contains a new argument, that the energy density of the fluctuating field which causes collapse should exert a gravitational force. This force can be repulsive, since this energy density can be negative. Speculative illustrations of cosmological implications are offered.Comment: 37 page

    A Study of Activated Processes in Soft Sphere Glass

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    On the basis of long simulations of a binary mixture of soft spheres just below the glass transition, we make an exploratory study of the activated processes that contribute to the dynamics. We concentrate on statistical measures of the size of the activated processes.Comment: 17 pages, 9 postscript figures with epsf, uses harvmac.te

    Language of Lullabies: The Russification and De-Russification of the Baltic States

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    This article argues that the laws for promotion of the national languages are a legitimate means for the Baltic states to establish their cultural independence from Russia and the former Soviet Union

    The Effects of Organic Compounds on Inhibition of Hydrogen Permeation Through a Mild Steel Membrane

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    The effectiveness of 5-(4-pyridyl)-2,7-nonadiene, and 1 phenyl-2-propyn-ol (PP) on inhibition of the hydrogen evolution reaction on a 1010 steel membrane and on the degree of hydrogen ingress into the membrane was determined. Hydrogen evolution rates and permeation currents were monitored as a function of time at different applied potentials. In the presence of 0.5 g/liter PP in the electrolyte, the hydrogen discharge and permeation current density were inhibited by 98 and 95%, respectively
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