36 research outputs found

    A protein essential for recovering oxygen evolution in cholate-treated chloroplasts

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    AbstractA novel method for the reconstitution of oxygen evolution in cholate-extracted spinach thylakoid membranes was established and a protein essential for the reconstitution was purified from cholate extracts. Purification of the protein was accomplished by chromatography on a DEAE-Sephacel column. This protein (Mr 17 000) was reinserted into vesicular membranes reconstituted from cholate-extracted thylakoids in the presence of 25% glycerol to reactivate oxygen evolution

    Nonrelativistic Quantum Particle in a Curved Space as a Constrained System

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    The operator and the functional formulations of the dynamics of constrained systems are explored for determining unambiguously the quantum Hamiltonian of a nonrelativistic particle in a curved space.Comment: 11 pages, latex, revtex, no figures. Accepted for publication in Phys. Lett.

    Canonical Transformations and Path Integral Measures

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    This paper is a generalization of previous work on the use of classical canonical transformations to evaluate Hamiltonian path integrals for quantum mechanical systems. Relevant aspects of the Hamiltonian path integral and its measure are discussed and used to show that the quantum mechanical version of the classical transformation does not leave the measure of the path integral invariant, instead inducing an anomaly. The relation to operator techniques and ordering problems is discussed, and special attention is paid to incorporation of the initial and final states of the transition element into the boundary conditions of the problem. Classical canonical transformations are developed to render an arbitrary power potential cyclic. The resulting Hamiltonian is analyzed as a quantum system to show its relation to known quantum mechanical results. A perturbative argument is used to suppress ordering related terms in the transformed Hamiltonian in the event that the classical canonical transformation leads to a nonquadratic cyclic Hamiltonian. The associated anomalies are analyzed to yield general methods to evaluate the path integral's prefactor for such systems. The methods are applied to several systems, including linear and quadratic potentials, the velocity-dependent potential, and the time-dependent harmonic oscillator.Comment: 28 pages, LaTe

    Classical Euclidean wormhole solutions in Palatini f(R~)f(\tilde{R}) cosmology

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    We study the classical Euclidean wormholes in the context of extended theories of gravity. With no loss of generality, we use the dynamical equivalence between f(R~)f(\tilde{R}) gravity and scalar-tensor theories to construct a point-like Lagrangian in the flat FRW space time. We first show the dynamical equivalence between Palatini f(R~)f(\tilde{R}) gravity and the Brans-Dicke theory with self-interacting potential, and then show the dynamical equivalence between the Brans-Dicke theory with self-interacting potential and the minimally coupled O'Hanlon theory. We show the existence of new Euclidean wormhole solutions for this O'Hanlon theory and, for an special case, find out the corresponding form of f(R~)f(\tilde{R}) having wormhole solution. For small values of the Ricci scalar, this f(R~)f(\tilde{R}) is in agreement with the wormhole solution obtained for higher order gravity theory R~+ϵR~2,ϵ<0\tilde{R}+\epsilon \tilde{R}^2,\epsilon<0.Comment: 11 page

    Reduced Effective Lagrangians

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    Effective Lagrangians, including those that are spontaneously broken, contain redundant terms. It is shown that the classical equations of motion may be used to simplify the effective Lagrangian, even when quantum loops are to be considered.Comment: 14 pages, no figures, PHYZZX, report #UM-TH-92-2

    Negative modes in the four-dimensional stringy wormholes

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    We study the Giddings-Strominger wormholes in string theories. We found negative modes among O(4)-symmetric fluctuations about the non-singular wormhole background. Hence the stringy wormhole contribution to the euclidean functional integral is purely imaginary. This means that the stringy wormhole is a bounce (not an instanton) and describes the nucleation and growth of wormholes in the Minkowski spacetime.Comment: 12 pages 2 figures, RevTe

    Quantum Hamilton-Jacobi equation

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    The nontrivial transformation of the phase space path integral measure under certain discretized analogues of canonical transformations is computed. This Jacobian is used to derive a quantum analogue of the Hamilton-Jacobi equation for the generating function of a canonical transformation that maps any quantum system to a system with a vanishing Hamiltonian. A formal perturbative solution of the quantum Hamilton-Jacobi equation is given.Comment: 4 pages, RevTe

    Brans-Dicke wormholes in the Jordan and Einstein frames

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    We examine the possibility of static wormhole solutions in the vacuum Brans-Dicke theory both in the original (Jordan) frame and in the conformally rescaled (Einstein) frame. It turns out that, in the former frame, wormholes exist only in a very narrow interval of the coupling parameter, viz., -3/2<omega<-4/3. It is shown that these wormholes are not traversable in practice. In the latter frame, wormhole solutions do not exist at all unless energy conditions are violated by hand.Comment: Minor errors corrected, uploaded for the benefit of the researcher
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