36 research outputs found
A protein essential for recovering oxygen evolution in cholate-treated chloroplasts
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
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
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 cosmology
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 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 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 having wormhole solution. For small
values of the Ricci scalar, this is in agreement with the
wormhole solution obtained for higher order gravity theory .Comment: 11 page
Reduced Effective Lagrangians
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
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
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
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