# Matt's arXiv selection, Monday 8 May 2006.

From: Matthew Davis <mdavis_at_physics.uq.edu.au>
Date: Mon, 8 May 2006 13:25:40 +1000 (EST)

The following message was sent to the matts_arxiv list by Matthew Davis <mdavis_at_physics.uq.edu.au>

Hi everyone,

This week I learnt that I should occasionally save the file with all the
abstracts in it, otherwise I might have to go through all those listings
twice!

On with the abstracts:

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Paper: cond-mat/0605048
Date: Tue, 2 May 2006 08:37:28 GMT (181kb)

Title: Deviation from one-dimensionality in stationary properties and
collisional dynamics of matter-wave solitons
Authors: Lev Khaykovich, Boris A. Malomed
Subj-class: Other
\\
By means of analytical and numerical methods, we study how the residual
three-dimensionality affects dynamics of solitons in an attractive
Bose-Einstein condensate loaded into a cigar-shaped trap. Based on an effective
1D Gross-Pitaevskii equation that includes an additional quintic self-focusing
term, generated by the tight transverse confinement, we find a family of exact
one-soliton solutions and demonstrate stability of the entire family, despite
the possibility of collapse in the 1D equation with the quintic self-focusing
nonlinearity. Simulating collisions between two solitons in the same setting,
we find a critical velocity, $V_{c}$, below which merger of identical in-phase
solitons is observed. Dependence of $V_{c}$ on the strength of the transverse
confinement and number of atoms in the solitons is predicted by means of the
perturbation theory and investigated in direct simulations. Symmetry breaking
in collisions of identical solitons with a nonzero phase difference is also
shown in simulations and qualitatively explained by means of an analytical
approximation.
\\ ( http://arXiv.org/abs/cond-mat/0605048 , 181kb)
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Paper: cond-mat/0605052
Date: Tue, 2 May 2006 10:45:37 GMT (791kb)

Title: Vortex localization in rotating clouds of bosons and fermions
Authors: S.M. Reimann, M. Koskinen, Y. Yu and M. Manninen
Subj-class: Mesoscopic Systems and Quantum Hall Effect; Strongly Correlated
Electrons
\\
Finite quantal systems at high angular momenta may exhibit vortex formation
and localization. These phenomena occur independent of the statistics of the
repulsively interacting particles, which may be of bosonic or fermionic nature.
We analyze the relation between vortex localization and formation of stable
Wigner molecules at high angular momenta in the view of particle-hole
duality.Trial wave functions for the vortex states and the corresponding
fermion-boson relations are discussed.
\\ ( http://arXiv.org/abs/cond-mat/0605052 , 791kb)
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Paper: cond-mat/0605056
Date: Tue, 2 May 2006 13:05:43 GMT (758kb)

Title: Dressed molecules in an optical lattice
Authors: K. B. Gubbels, D. B. M. Dickerscheid, and H. T. C. Stoof
Subj-class: Statistical Mechanics
\\
We present the theory of an atomic gas in an optical lattice near a Feshbach
resonance. We derive from first principles a generalized Hubbard model, that
incorporates all the relevant two-body physics exactly, except for the
background atom-atom scattering. For most atoms the background interactions are
negligible, but this is not true for lithium-6, which has an exceptionally
large background scattering length near the experimentally relevant Feshbach
resonance at 834 G. Therefore, we show how to include background atom-atom
scattering by solving the on-site two-body Feshbach problem exactly. We apply
the obtained solution to lithium-6 and find that the background interactions
indeed have a significant effect in this case.
\\ ( http://arXiv.org/abs/cond-mat/0605056 , 758kb)
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Paper (*cross-listing*): math-ph/0605002
Date: Mon, 1 May 2006 05:14:22 GMT (24kb)

Title: Feynman cycles in the Bose gas
Authors: Daniel Ueltschi
Subj-class: Mathematical Physics; Statistical Mechanics
MSC-class: 82B10; 82B21; 82B26; 82D50
\\
We study the lengths of the cycles formed by trajectories in the Feynman-Kac
representation of the Bose gas. We discuss the occurrence of infinite cycles
and their relation to Bose-Einstein condensation.
\\ ( http://arXiv.org/abs/math-ph/0605002 , 24kb)
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Paper: quant-ph/0605020
Date: Tue, 2 May 2006 01:06:10 GMT (366kb)

Title: The Super-Strong Coupling Regime of Cavity Quantum Electrodynamics
Authors: D. Meiser, P. Meystre
Comments: revtex, 4 pages, 4 figures
\\
We describe a qualitatively new regime of cavity quantum electrodynamics, the
super strong coupling regime. This regime is characterized by atom-field
coupling strengths of the order of the free spectral range of the cavity,
resulting in a significant change in the spatial mode functions of the light
field. It can be reached in practice for cold atoms trapped in an optical
dipole potential inside the resonator. We present a nonperturbative scheme that
allows us to calculate the frequencies and linewidths of the modified field
modes, thereby providing a good starting point for a quantization of the
theory.
\\ ( http://arXiv.org/abs/quant-ph/0605020 , 366kb)
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Paper: quant-ph/0605023
Date: Tue, 2 May 2006 08:59:51 GMT (97kb)

Title: A possible approach to improve sensitivity of Michelson interferometer
Authors: Jian Fu
\\
We propose a possible approach to achieve an 1/N sensitivity of Michelson
interferometer by using a properly designed random phase modulation. Although,
the $\sqrt{N}$ precision improvement might not be achieved due to the
complication of the random phase modulation, it can help interferometers such
as LIGO to reach higher sensitivity.
\\ ( http://arXiv.org/abs/quant-ph/0605023 , 97kb)
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Paper: quant-ph/0605029
Date: Tue, 2 May 2006 18:48:00 GMT (8kb)

Title: Field fluctuations near a conducting plate and Casimir-Polder forces in
the presence of boundary conditions
Authors: S. Spagnolo, R. Passante and L. Rizzuto
\\
We consider vacuum fluctuations of the quantum electromagnetic field in the
presence of an infinite and perfectly conducting plate. We evaluate how the
change of vacuum fluctuations due to the plate modifies the Casimir-Polder
potential between two atoms placed near the plate. We use two different methods
to evaluate the Casimir-Polder potential in the presence of the plate. They
also give new insights on the role of boundary conditions in the Casimir-Polder
interatomic potential, as well as indications for possible generalizations to
more complicated boundary conditions.
\\ ( http://arXiv.org/abs/quant-ph/0605029 , 8kb)
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Paper: physics/0605018
Date: Tue, 2 May 2006 12:02:19 GMT (201kb)

Title: Long-lived Bloch oscillations with bosonic Sr atoms and application to
gravity measurement at micrometer scale
Authors: G. Ferrari, N. Poli, F. Sorrentino, G. M. Tino
Subj-class: Atomic Physics
\\
We report on the observation of Bloch oscillations on the unprecedented time
scale of severalseconds. The experiment is carried out with ultra-cold bosonic
strontium-88 loaded into a vertical optical standing wave. The negligible
atom-atom elastic cross section and the absence of spin makes $^{88}$Sr an
almost ideal Bose gas insensitive to typical mechanisms of decoherence due to
thermalization and to external stray fields. The small size enables precision
measurements of forces at micrometer scale. This is a challenge in physics for
studies of surfaces, Casimir effects, and searches for deviations from
Newtonian gravity predicted by theories beyond the standard model.
\\ ( http://arXiv.org/abs/physics/0605018 , 201kb)
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Paper: physics/0605019
Date: Tue, 2 May 2006 15:35:17 GMT (191kb)

Title: Formation of ultracold LiCs molecules
Authors: Stephan D. Kraft, Peter Staanum, Joerg Lange, Leif Vogel, Roland
Wester, Matthias Weidemueller
Subj-class: Atomic Physics
\\
We present the first observation of ultracold LiCs molecules. The molecules
are formed in a two-species magneto-optical trap and detected by two-photon
ionization and time-of-flight mass spectrometry. The production rate
coefficient is found to be in the range $10^{-18}\unit{cm^3s^{-1}}$ to
$10^{-16}\unit{cm^3s^{-1}}$, at least an order of magnitude smaller than for
other heteronuclear diatomic molecules directly formed in a magneto-optical
trap.
\\ ( http://arXiv.org/abs/physics/0605019 , 191kb)
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Paper: physics/0605017
Date: Tue, 2 May 2006 09:53:20 GMT (285kb)

Title: Soliton control in fading optical lattices
Authors: Yaroslav V. Kartashov, Victor A. Vysloukh, Lluis Torner
Comments: 12 pages, 3 figures, to appear in Optics Letters
Subj-class: Optics
\\
We predict new phenomena, such as soliton steering and soliton fission, in
optical lattices that fade away exponentially along the propagation direction.
Such lattices, featuring tunable decay rates, arise in photorefractive crystals
in the wavelength range 360-400 nm. We show that the predicted phenomena offer
different opportunities for soliton control.
\\ ( http://arXiv.org/abs/physics/0605017 , 285kb)
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Paper: physics/0604082
replaced with revised version Tue, 2 May 2006 19:53:10 GMT (252kb)

Title: Atom interferometer as a selective sensor of rotation or gravity
Authors: B. Dubetsky and M. A. Kasevich
Subj-class: Atomic Physics
\\ ( http://arXiv.org/abs/physics/0604082 , 231kb)
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Paper: cond-mat/0605085
Date: Wed, 3 May 2006 12:36:57 GMT (41kb)

Title: Anomalous specific heat jump in a two-component ultracold Fermi gas
Authors: Armen Sedrakian, Herbert M\"uther, Artur Polls
Subj-class: Superconductivity; Statistical Mechanics
\\
We study the temperature-asymmetry phase diagram of a Fermi gas with spin
population imbalance. The imbalance suppresses the pairing in general, and the
temperature dependence of the gap and thermodynamic functions is analogous to
the ordinary BCS state in the high-temperature domain. Anomalies appear in the
low temperature domain: the pairing gap decreases with the temperature and the
entropy of the superfluid is enhanced above the entropy of the normal state.
For large asymmetries the gap shows a reentrance effect - it exists in a
temperature domain bounded by two critical temperatures. This effect leads to
an anomalous second jump in the specific heat of the superfluid, which can be
measured in calorimetric experiments.
\\ ( http://arXiv.org/abs/cond-mat/0605085 , 41kb)
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Paper: cond-mat/0605090
Date: Wed, 3 May 2006 13:17:15 GMT (489kb)

Title: Fast energy transfer mediated by multi-quanta bound states in a
nonlinear quantum lattice
Authors: Cyril Falvo (LPM), Vincent Pouthier (LPM), J. C. Eilbeck
Proxy: ccsd ccsd-00023659
Subj-class: Other
\\
By using a Generalized Hubbard model for bosons, the energy transfer in a
nonlinear quantum lattice is studied, with special emphasis on the interplay
between local and nonlocal nonlinearity. For a strong local nonlinearity, it is
shown that the creation of v quanta on one site excites a soliton band formed
by bound states involving v quanta trapped on the same site. The energy is
first localized on the excited site over a significant timescale and then
slowly delocalizes along the lattice. As when increasing the nonlocal
nonlinearity, a faster dynamics occurs and the energy propagates more rapidly
along the lattice. Nevertheless, the larger is the number of quanta, the slower
is the dynamics. However, it is shown that when the nonlocal nonlinearity
reaches a critical value, the lattice suddenly supports a very fast energy
propagation whose dynamics is almost independent on the number of quanta. The
energy is transfered by specific bound states formed by the superimposition of
states involving v-p quanta trapped on one site and p quanta trapped on the
nearest neighbour sites, with p=0,..,v-1. These bound states behave as
independent quanta and they exhibit a dynamics which is insensitive to the
nonlinearity and controlled by the single quantum hopping constant.
\\ ( http://arXiv.org/abs/cond-mat/0605090 , 489kb)
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Paper: cond-mat/0605093
Date: Wed, 3 May 2006 16:21:11 GMT (55kb)

Title: Nonergodic Brownian Dynamics and the Fluctuation-Dissipation Theorem
Authors: Jing-Dong Bao, Yi-Zhong Zhuo, Fernando A. Oliveira and Peter H\"anggi
Subj-class: Statistical Mechanics
\\
Nonergodic Brownian motion is elucidated within the framework of the
generalized Langevin equation. For thermal noise yielding either a vanishing or
a divergent zero-frequency friction strength, the non-Markovian Browninan
dynamics exhibits a riveting, anomalous diffusion behavior being characterized
by a ballistic or possibly also a localized dynamics. As a consequence, such
tailored thermal noise may cause a net acceleration of directed transport in a
rocking Brownian motor. Two notable conditions for the thermal noise are
identified in order to guarantee the fluctuation-dissipation theorem of first
kind.
\\ ( http://arXiv.org/abs/cond-mat/0605093 , 55kb)
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Paper: cond-mat/0605097
Date: Wed, 3 May 2006 17:56:12 GMT (25kb)

Title: Decoherence and Quantum Walks: anomalous diffusion and ballistic tails
Authors: Nikolay Prokof'ev and Philip Stamp
Subj-class: Other
\\
The common perception is that strong coupling to the environment will always
render the evolution of the system density matrix quasi-classical (in fact,
diffusive) in the long time limit. We present here a counter-example, in which
a particle makes quantum transitions between the sites of a d-dimensional
hypercubic lattice whilst strongly coupled to a bath of two-level systems which
'record' the transitions. The long-time evolution of an initial wave packet
is found to be most unusual: the mean square displacement of the particle
density matrix shows long-range ballitic behaviour, but simultaneously a kind
of weakly-localised behaviour near the origin. This result may have important
implications for the design of quantum computing algorithms, since it describes
a class of quantum walks.
\\ ( http://arXiv.org/abs/cond-mat/0605097 , 25kb)
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Paper: cond-mat/0605099
Date: Wed, 3 May 2006 19:31:18 GMT (709kb)

Title: Strongly Interacting Atoms and Molecules in a 3D Optical Lattice
Authors: Michael K\"ohl, Kenneth G\"unter, Thilo St\"oferle, Henning Moritz,
and Tilman Esslinger
Subj-class: Other
Journal-ref: J. Phys. B: At. Mol. Opt. Phys. 39 (2006) S47-S56
DOI: 10.1088/0953-4075/39/10/S05
\\
We report on the realization of a strongly interacting quantum degenerate gas
of fermionic atoms in a three-dimensional optical lattice. We prepare a
band-insulating state for a two-component Fermi gas with one atom per spin
state per lattice site. Using a Feshbach resonance, we induce strong
interactions between the atoms. When sweeping the magnetic field from the
repulsive side towards the attractive side of the Feshbach resonance we induce
a coupling between Bloch bands leading to a transfer of atoms from the lowest
band into higher bands. Sweeping the magnetic field across the Feshbach
resonance from the attractive towards the repulsive side leads to two-particle
bound states and ultimately to the formation of molecules. From the fraction of
formed molecules we determine the temperature of the atoms in the lattice.
\\ ( http://arXiv.org/abs/cond-mat/0605099 , 832kb)
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Paper (*cross-listing*): nlin.SI/0605006
Date: Tue, 2 May 2006 15:25:16 GMT (21kb)

Title: Nonlinear Dynamics of Quantum Systems and Soliton Theory
Authors: Eldad Bettelheim, Alexander G. Abanov, Paul Wiegmann
Subj-class: Exactly Solvable and Integrable Systems; Other
\\
We show that space-time evolution of one-dimensional fermionic systems is
described by nonlinear equations of soliton theory. We identify a space-time
dependence of a matrix element of fermionic systems related to the {\it
Orthogonality Catastrophe} or {boundary states} with the $\tau$-function of the
modified KP-hierarchy. The established relation allows to apply the apparatus
of soliton theory to the study of non-linear aspects of quantum dynamics. We
also describe a {\it bosonization in momentum space} - a representation of a
fermion operator by a Bose field in the presence of a boundary state.
\\ ( http://arXiv.org/abs/nlin/0605006 , 21kb)
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Paper: quant-ph/0605036
Date: Wed, 3 May 2006 11:20:10 GMT (9kb)

Title: An optimal entanglement criterion for mixed quantum states
Authors: Heinz-Peter Breuer
\\
We develop a strong and computationally simple entanglement criterion. The
criterion is based on an elementary positive map Phi which operates on state
spaces with even dimension N >= 4. It is shown that Phi detects many entangled
states with positive partial transposition (PPT) and that it leads to a class
of optimal entanglement witnesses. This implies that there are no other
witnesses which can detect more entangled PPT states. The map Phi yields a
systematic method for the explicit construction of high-dimensional manifolds
of bound entangled states.
\\ ( http://arXiv.org/abs/quant-ph/0605036 , 9kb)
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Paper: physics/0605028
Date: Wed, 3 May 2006 03:13:55 GMT (280kb)

Title: Effect of Magnetization Inhomogeneity on Magnetic Microtraps for Atoms
Authors: S. Whitlock, B. V. Hall, T. Roach, R. Anderson, P. Hannaford and A. I.
Sidorov
Subj-class: Atomic Physics
\\
We report on the origin of fragmentation of ultracold atoms observed on a
permanent magnetic film atom chip. A novel technique is used to characterize
small spatial variations of the magnetic field near the film surface using
radio frequency spectroscopy of the trapped atoms. Direct observations indicate
the fragmentation is due to a corrugation of the magnetic potential caused by
long range inhomogeneity in the film magnetization. A model which takes into
account two-dimensional variations of the film magnetization is consistent with
the observations.
\\ ( http://arXiv.org/abs/physics/0605028 , 280kb)
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Paper: physics/0605034
Date: Wed, 3 May 2006 16:47:16 GMT (930kb)

Title: Kilohertz-resolution spectroscopy of cold atoms with an optical
frequency comb
Authors: T. M. Fortier, Y. Le Coq, J. E. Stalnaker, D. Ortega, S. A. Diddams,
C. W. Oates and L. Hollberg
Subj-class: Atomic Physics
\\
We have performed sub-Doppler spectroscopy on the narrow intercombination
line of cold calcium atoms using the amplified output of a femtosecond laser
frequency comb. Injection locking of a 657-nm diode laser with a femtosecond
comb allows for two regimes of amplification, one in which many lines of the
comb are amplified, and one where a single line is predominantly amplified. The
output of the laser in both regimes was used to perform kilohertz-level
spectroscopy. This experiment demonstrates the potential for high-resolution
absolute-frequency spectroscopy over the entire spectrum of the frequency comb
output using a single high-finesse optical reference cavity.
\\ ( http://arXiv.org/abs/physics/0605034 , 930kb)
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Paper: cond-mat/0605102
Date: Wed, 3 May 2006 20:07:03 GMT (243kb)

Title: Topological defects and the superfluid transition of the $s=1$ spinor
condensate in two dimensions
Authors: Subroto Mukerjee, Cenke Xu, and J. E. Moore
Subj-class: Other
\\
The $s=1$ spinor Bose condensate at zero temperature supports ferromagnetic
and polar phases that combine magnetic and superfluid ordering. The polar
condensate at finite temperature in two dimensions is shown to have a nematic
or paired superfluid phase with algebraic order in $\exp(2 i \theta)$,where
$\theta$ is the superfluid phase, and no magnetic order. The
Kosterlitz-Thouless transition out of this phase is driven by unbinding of
half-vortices (the spin-disordered version of the combined spin and phase
defects found by Zhou), and the anomalous $8 T_c / \pi$ stiffness jump at the
transition is confirmed in numerical simulations. Experimental observation of
the anomalous jump would be direct confirmation of a phase transition
controlled by unbinding of half-vortices.
\\ ( http://arXiv.org/abs/cond-mat/0605102 , 243kb)
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Paper: cond-mat/0605121
Date: Thu, 4 May 2006 16:51:05 GMT (14kb)

Title: Sweeping from the superfluid to Mott phase in the Bose-Hubbard model
Authors: Ralf Sch\"utzhold, Michael Uhlmann, Yan Xu, Uwe R. Fischer
Comments: 4 pages of RevTex4, 1 figure
Subj-class: Statistical Mechanics
\\
We study the sweep through the quantum phase transition from the superfluid
to the Mott state for the Bose-Hubbard model with a time-dependent tunneling
rate $J(t)$. In the experimentally relevant case of exponential decay,
$J(t)\propto e^{-\gamma t}$, an adapted mean-field expansion for large
fillings~$n$ yields a scaling solution for the fluctuations. This enables us to
analytically calculate the evolution of the number and phase variations
(on-site) and correlations (off-site) for slow ($\gamma\ll\mu$), intermediate,
and fast (non-adiabatic $\gamma\gg\mu$) sweeps, where $\mu$ is the chemical
potential. Finally, we derive the dynamical decay of the off-diagonal
long-range order as well as the temporal shrinkage of the superfluid fraction
in a persistent ring-current setup.
\\ ( http://arXiv.org/abs/cond-mat/0605121 , 14kb)
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Paper: cond-mat/0604638
replaced with revised version Thu, 4 May 2006 18:38:17 GMT (363kb)

Title: Surface tension in population imbalanced unitary Fermi gases
Authors: Theja N. De Silva, Erich J. Mueller
Subj-class: Other
\\ ( http://arXiv.org/abs/cond-mat/0604638 , 363kb)
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Paper: quant-ph/0602180
replaced with revised version Thu, 4 May 2006 13:15:16 GMT (12kb)

Title: On the detectability of quantum radiation in Bose-Einstein condensates
Authors: Ralf Sch\"utzhold
\\ ( http://arXiv.org/abs/quant-ph/0602180 , 12kb)
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And if you've read this far, here's one just for fun:

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Paper: physics/0605040
Date: Thu, 4 May 2006 11:13:35 GMT (154kb)

Title: Scattering of a Baseball by a Bat
Authors: Rod Cross and Alan M. Nathan
Comments: Accepted for publication in American Journal of Physics
Subj-class: Popular Physics
\\
A ball can be hit faster if it is projected without spin but it can be hit
farther if it is projected with backspin. Measurements are presented in this
paper of the tradeoff between speed and spin for a baseball impacting a
baseball bat. The results are inconsistent with a collision model in which the
ball rolls off the bat and instead imply tangential compliance in the ball, the
bat, or both. If the results are extrapolated to the higher speeds that are
typical of the game of baseball, they suggest that a curveball can be hit with
greater backspin than a fastball, but by an amount that is less than would be
the case in the absence of tangential compliance.
\\ ( http://arXiv.org/abs/physics/0605040 , 154kb)
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--
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Dr M. J. Davis,               Senior Lecturer in Physics
School of Physical Sciences,  email: mdavis_at_physics.uq.edu.au
University of Queensland,     ph   : +61 7 334 69824
Brisbane, QLD 4072,           fax  : +61 7 336 51242
Australia.                    http://www.physics.uq.edu.au/people/mdavis/
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Received on Mon May 08 2006 - 13:25:40 EST

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