From: Matthew Davis <mdavis_at_physics.uq.edu.au>

Date: Tue, 19 May 2009 08:44:33 +1000

Date: Tue, 19 May 2009 08:44:33 +1000

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

Dear subscribers,

We have Simon Haine to thank for this week's list. There are 18 new preprints

and 9 replacements:

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arXiv:0902.4707

Date: Thu, 26 Feb 2009 21:31:39 GMT (901kb)

Title: On-site correlations in optical lattices: band mixing to coupled quantum

Hall puddles

Authors: Kaden R. A. Hazzard and Erich J. Mueller (Cornell)

Categories: cond-mat.other

Comments: 4 pages, 4 figures

\\

We extend the standard Bose-Hubbard model to capture arbitrarily strong

on-site correlations. In addition to being important for quantitatively

modeling experiments, for example, with Rubidium atoms, these correlations must

be included to describe more exotic situations. Two such examples are when the

interactions are made large via a Feshbach resonance, or when each site rotates

rapidly, making a coupled array of quantum Hall puddles. Remarkably, even the

mean field approximation to our model includes all on-site correlations. We

describe how these on-site correlations manifest themselves in the system's

global properties: modifying the phase diagram and depleting the condensate.

\\ ( http://arxiv.org/abs/0902.4707 , 901kb)

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arXiv:0902.4734

Date: Fri, 27 Feb 2009 01:11:49 GMT (94kb)

Title: Ultracold Bosons with 3-Body Attractive Interactions in an Optical

Lattice

Authors: E. Fersino, B.A. Malomed, G. Mussardo, A. Trombettoni

Categories: cond-mat.stat-mech

Comments: Special issue of European Physical Journal B on the conference

"Theory of Quantum Gases and Quantum Coherence" held in Grenoble, 2008

\\

We study the effect of an optical lattice (OL) on the ground-state properties

of one-dimensional ultracold bosons with three-body attraction and two-body

repulsion, which are described by a cubic-quintic Gross-Pitaevskii equation

with a periodic potential. Without the OL and with a vanishing two-body

interaction term, soliton solutions of the Townes type are possible only at a

critical value of the three-body interaction strength, at which an infinite

degeneracy of the ground-state occurs; a repulsive two-body interaction makes

such localized solutions unstable. We show that the OL opens a stability window

around the critical point when the strength of the periodic potential is above

a critical threshold. We also consider the effect of an external parabolic

trap, studying how the stability of the solitons depends on matching between

minima of the periodic potential and the minimum of the parabolic trap.

\\ ( http://arxiv.org/abs/0902.4734 , 94kb)

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arXiv:0902.4746

Date: Fri, 27 Feb 2009 02:55:08 GMT (603kb)

Title: Massless Dirac Fermions in a Square Optical Lattice

Authors: Jing-Min Hou, Wen-Xing Yang, Xiong-Jun Liu

Categories: cond-mat.other

\\

We propose a novel scheme to simulate and observe massless Dirac fermions

with cold atoms in a square optical lattice. A U(1) adiabatic phase is created

by two laser beams for the tunneling of atoms between neighbor lattice sites.

Properly adjusting the tunneling phase, we find that the energy spectrum has

conical points in per Brillouin zone where band crossing occurs. Near these

crossing points the quasiparticles and quasiholes can be considered as massless

Dirac fermions. Furthermore, the anisotropic effects of massless Dirac fermions

are obtained in the present square lattice model. The Dirac fermions as well as

the anisotropic behaviors realizeded in our system can be experimentally

detected with the Bragg spectroscopy technique.

\\ ( http://arxiv.org/abs/0902.4746 , 603kb)

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arXiv:0902.4775

Date: Fri, 27 Feb 2009 09:15:26 GMT (39kb)

Title: Asymptotic solutions of a nonlinear diffusive equation in the framework

of $\kappa$-generalized statistical mechanics

Authors: T. Wada and A.M. Scarfone

Categories: cond-mat.stat-mech

Comments: Submitted to EPJB

\\

The asymptotic behavior of a nonlinear diffusive equation obtained in the

framework of the $\kappa$-generalized statistical mechanics is studied. The

analysis based on the classical Lie symmetry shows that the $\kappa$-Gaussian

function is not a scale invariant solution of the generalized diffusive

equation. Notwithstanding, several numerical simulations, with different

initial conditions, show that the solutions asymptotically approach to the

$\kappa$-Gaussian function. Simple argument based on a time-dependent

transformation performed on the related $\kappa$-generalized Fokker-Planck

equation, supports this conclusion.

\\ ( http://arxiv.org/abs/0902.4775 , 39kb)

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arXiv:0902.4792

Date: Fri, 27 Feb 2009 10:46:30 GMT (35kb)

Title: Population Dynamics of a Spin-1 Bose Gas Above the Bose-Einstein

Transition Temperature

Authors: Yuki Endo and Tetsuro Nikuni

Categories: cond-mat.other

Comments: 6pages,1figure

\\

We study population dynamics of a trapped spin-1 Bose gas above the

Bose-Einstein transition temperature. Starting from the semiclassical kinetic

equation for a spin-1 gas, we derive a coupled rate equations for the

populations of internal states. Solving the rate equations, we discuss the

dynamical evolution of spin populations. We also estimate the characteristic

timescale in which the system reaches equilibrium. Finally, we briefly discuss

how the presence of the condensate will affect the population dynamics.

\\ ( http://arxiv.org/abs/0902.4792 , 35kb)

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arXiv:0902.4628 (*cross-listing*)

Date: Thu, 26 Feb 2009 16:40:16 GMT (8kb)

Title: Is it possible to stimulate nuclear alpha decay by superfluid helium?

Authors: A. L. Barabanov

Categories: nucl-th cond-mat.stat-mech nucl-ex

Comments: 4 pages

\\

It is suggested that superfluid helium (condensate of 4-He atoms) may

stimulate nuclear alpha decay in situation when alpha emitter moves through

superfluid helium, while the back-emitted alpha particle comes to rest. It is

shown that the probability of stimulated alpha decay may be sizable enough to

be detected.

\\ ( http://arxiv.org/abs/0902.4628 , 8kb)

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arXiv:0902.4898

Date: Fri, 27 Feb 2009 19:19:20 GMT (8kb)

Title: Effective Quantum Time Travel

Authors: George Svetlichny

Categories: quant-ph

Comments: 8 pages, 6 figures

\\

The quantum teleportation protocol can be used to probabilistically simulate

a quantum circuit with backward-in-time connections. This allows us to analyze

some conceptual problems of time travel in the context of physically realizable

situations, to realize encrypted measurements of future states for which the

decryption key becomes available only after the state is created, and to

probabilistically realize a multistage quantum state processing within the time

needed to complete only one stage. The probabilistic nature of the process

resolves any paradox.

\\ ( http://arxiv.org/abs/0902.4898 , 8kb)

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arXiv:0902.4692 (*cross-listing*)

Date: Thu, 26 Feb 2009 20:33:23 GMT (287kb)

Title: The Tiger and the Sun: Solar Power Plants and Wildlife Sanctuaries

Authors: Michael McGuigan

Categories: q-bio.PE physics.soc-ph

Comments: 19 pages, 4 tables, 9 figures

\\

We discuss separate and integrated approaches to building scalable solar

power plants and wildlife sanctuaries. Both solar power plants and wildlife

sanctuaries need a lot of land. We quantify some of the requirements using

various estimates of the rate of solar power production as well as the rate of

adding wildlife to a sanctuary over the time range 2010-2050. We use population

dynamics equations to study the evolution of solar energy and tiger populations

up to and beyond 2050.

\\ ( http://arxiv.org/abs/0902.4692 , 287kb)

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arXiv:0903.0016

Date: Sat, 28 Feb 2009 09:09:00 GMT (59kb)

Title: Magnon BEC in superfluid 3He-A

Authors: Yu.M. Bunkov and G.E. Volovik

Categories: cond-mat.other cond-mat.dis-nn

Comments: 6 pages, 2 figures, JETP Letters style

\\

The new mode of magnetization precession in superfluid 3He-A in a squeezed

aerogel has been recently reported. We consider this mode in terms of the

Bose-Einstein condensation (BEC) of magnons. The difference between magnon BEC

states in 3He-A and in 3He-B is discussed.

\\ ( http://arxiv.org/abs/0903.0016 , 59kb)

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arXiv:0903.0108

Date: Sat, 28 Feb 2009 21:03:08 GMT (378kb)

Title: Accessing the Neel phase of ultracold fermionic atoms in a simple-cubic

optical lattice

Authors: C.J.M. Mathy, D.A. Huse

Categories: cond-mat.str-el

Comments: 7 pages, 4 figures

\\

We examine the phase diagram of a simple-cubic optical lattice half-filled by

two species of fermionic atoms with a repulsive s-wave contact interaction. We

use the Hartree approximation in the regime of weaker interactions, and a

Hubbard model approximation in the Mott insulating phase. The regime where the

Neel phase of this system is likely to be most accessible to experiments is at

intermediate lattice strengths and interactions, and our two approximations

agree fairly well in this regime. We discuss the various issues that may

determine where in this phase diagram the Neel phase is first produced and

detected experimentally, and analyze the quantum phases that occur in the

intermediate lattice strength regime.

\\ ( http://arxiv.org/abs/0903.0108 , 378kb)

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arXiv:0903.0146

Date: Sun, 1 Mar 2009 14:50:08 GMT (384kb)

Title: Stable Bloch oscillations of cold atoms with time dependent interaction

Authors: C. Gaul, R. P. A. Lima, E. Diaz, C. A. Mueller, and F. Dominguez-Adame

Categories: cond-mat.other

\\

We investigate Bloch oscillations of interacting cold atoms in a mean-field

framework. In general, atom-atom interaction causes dephasing and destroys

Bloch oscillations. Here, we show that Bloch oscillations are persistent if the

interaction is modulated harmonically with suitable frequency and phase. For

other modulations, Bloch oscillations are rapidly damped. We explain this

behavior in terms of collective coordinates whose Hamiltonian dynamics permits

to predict a whole family of stable solutions. In order to describe also the

unstable cases, we carry out a stability analysis for Bogoliubov excitations.

Using Floquet theory, we are able to predict the unstable modes as well as

their growth rate, found to be in excellent agreement with numerical

simulations.

\\ ( http://arxiv.org/abs/0903.0146 , 384kb)

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arXiv:0903.0151

Date: Sun, 1 Mar 2009 16:25:51 GMT (725kb)

Title: Dissipation-induced coherent structures in Bose-Einstein condensates

Authors: Valeriy A. Brazhnyi, Vladimir V. Konotop, Victor M. Perez-Garcia,

Herwig Ott

Categories: cond-mat.other

Comments: 4pages, 7 figures

\\

We discuss how to engineer the phase and amplitude of a complex order

parameter using localized dissipative perturbations. Our results are applied to

generate and control various types of atomic nonlinear matter waves (solitons)

by means of localized dissipative defects.

\\ ( http://arxiv.org/abs/0903.0151 , 725kb)

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arXiv:0903.0260

Date: Mon, 2 Mar 2009 11:24:44 GMT (1569kb)

Title: Nonperturbative thermodynamics of an interacting Bose gas

Authors: S. Floerchinger and C. Wetterich

Categories: cond-mat.other

Comments: 10 pages, 15 figures

\\

We discuss the thermodynamics of a non-relativistic gas of bosons with a

local repulsive interaction. In particular, we compute the temperature and

density dependence of pressure, energy and entropy-density, superfluid and

condensate-fraction, correlation length, specific heat, isothermal and

adiabatic compressibility and various sound velocities. The T->0 limit

approaches the quantum phase transition, while the universal critical behavior

of a classical second order phase transition in the O(2) universality class

determines the region around the critical temperature. Our non-perturbative

flow equations based on exact functional renormalization cover all regions in

the phase diagram.

\\ ( http://arxiv.org/abs/0903.0260 , 1569kb)

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arXiv:0902.4725 (*cross-listing*)

Date: Thu, 26 Feb 2009 23:31:15 GMT (11kb)

Title: Mapping the Two-Component Atomic Fermi Gas to the Nuclear Shell-Model

Authors: C. \"Ozen and N.T. Zinner

Categories: nucl-th cond-mat.str-el

Comments: 7 pages, no figures. Revtex4

\\

The physics of two-component fermi systems is now frequently addressed in

laboratories. Usually this is done for large samples of tens to hundreds of

thousands of particles. However, there are now groups working towards few-body

systems (1-100 particles) in very tight traps where the shell structure of the

external potential becomes important. This is analogous to the situation

encountered in nuclear structure physics. Here the state-of-the-art method is

large-scale diagonalization of the interaction hamiltonian in an appropriate

model space. We map the atomic physics problem onto the nuclear shell-model and

show that the two-component atomic fermi gas with zero-range interaction does

not suffer from the famous fermionic sign problem, making Quantum Monte Carlo

methods feasible.

\\ ( http://arxiv.org/abs/0902.4725 , 11kb)

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arXiv:0903.0724

Date: Wed, 4 Mar 2009 10:39:55 GMT (1120kb,D)

Title: Coherent transport of atomic wave packets in amplitude-modulated optical

lattices under the effect of gravity

Authors: A. Alberti, G. Ferrari, V. V. Ivanov and G. M. Tino

Categories: quant-ph

\\

We report on the experimental realization of a dynamical control of transport

of ultra-cold atoms loaded in an accelerated and amplitude-modulated 1D optical

lattice potential. We tailor the dispersion law of traveling wave packets and

we show the ability to reversibly switch between localization regime and

tunneling one. From this we demonstrate a novel atom mirror in optical lattices

by reversing the group velocity of the atoms independently of their momentum

state. We discuss a direct application of this transport mechanism to measure

forces at micrometric spatial scales.

\\ ( http://arxiv.org/abs/0903.0724 , 1120kb)

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arXiv:0903.0968

Date: Thu, 5 Mar 2009 11:54:10 GMT (107kb)

Title: "Scars" in Bose-Einstein condensates?

Authors: Nadav Katz and Oded Agam

Categories: cond-mat.other

Comments: 4 pages, 1 figure

\\

Parametric excitation of a Bose-Einstein condensate (BEC) can be realized by

periodically changing the interaction strength between the atoms. Above

threshold, this excitation modulates the condensate density. We show that when

the condensate is trapped in a potential well of irregular shape, such as the

stadium billiard, the density waves can be strongly scarred along the shortest

periodic orbits of rays moving within the confining potential. However, while

single-particle wave functions of chaotic systems may exhibit rich scarring

patterns, we find that nonlinear effects in BEC hinder the excitation of long

scars. Scars are found to be unstable to dephasing. This property provides a

sensitive probe for measuring decoherence in BECs.

\\ ( http://arxiv.org/abs/0903.0968 , 107kb)

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arXiv:0903.0997

Date: Thu, 5 Mar 2009 14:10:09 GMT (9kb)

Title: New application of Dirac's representation: N-mode squeezing enhanced

operator and squeezed state

Authors: Xue-xiang Xu, Li-yun Hu and Hong-yi Fan

Categories: quant-ph

Comments: 8 pages, no figure

\\

It is known that exp[i\lamda(Q_1P_1-i/2)] is a unitary single-mode squeezing

operator, where Q_1,P_1 are the coordinate and momentum operators,

respectively. In this paper we employ Dirac's coordinate representation to

prove that the exponential operator S_{n}=Exp[i\lamda

sum_{i=1}^{n}](Q_{i}P_{i+1}+Q_{i+1}P_{i}))], (Q_{n+1}=Q_1P_{n+1}=P_1), is a

n-mode squeezing operator which enhances the standard squeezing. By virtue of

the technique of integration within an ordered product of operators we derive

S_{n}'s normally ordered expansion and obtain new n-mode squeezed vacuum

states, its Wigner function is calculated by using the Weyl ordering invariance

under similar transformations.

\\ ( http://arxiv.org/abs/0903.0997 , 9kb)

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arXiv:0903.0998 (*cross-listing*)

Date: Thu, 5 Mar 2009 02:32:14 GMT (25kb)

Title: Modification of spin mixing of spinor BEC by cavity QED coupling

Authors: Ma Luo, Chengguang Bao, Zhibing Li

Categories: physics.atm-clus physics.optics

Comments: 5 pages, 1 figure

\\

Dressed states of spinor Bose-Einstein condensates of spin-1 atoms coupling

with optical cavity modes with far off resonance frequency are investigated.

The exact solution of time evolution of population of spin component is

derived, and the numerical result shows that the evolution is different from

spin mixing without the coupling. Due to the coupling with the atoms, the

photon state also evolute to different optical cavity modes.

\\ ( http://arxiv.org/abs/0903.0998 , 25kb)

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The replacements:

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arXiv:0809.2387

replaced with revised version Fri, 27 Feb 2009 03:37:10 GMT (77kb)

Title: Absence of Anomalous Tunneling of Bogoliubov Excitations for Arbitrary

Potential Barrier under the Critical Condensate Current

Authors: Daisuke Takahashi and Yusuke Kato

Categories: cond-mat.other

Comments: 4 pages, 1 figure

Journal-ref: J. Phys. Soc. Jpn. 78, 023001 (2009)

DOI: 10.1143/JPSJ.78.023001

\\ ( http://arxiv.org/abs/0809.2387 , 77kb)

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arXiv:0812.1387

replaced with revised version Fri, 27 Feb 2009 13:25:58 GMT (355kb)

Title: Effective three-body interactions and decoherence of coherent atom

states in optical lattices

Authors: P.R. Johnson, E. Tiesinga, J.V. Porto, C.J. Williams

Categories: quant-ph

Comments: 5 pages, 3 figures. Added curve showing estimated effects of

inhomogeneities on collapse and revival in contrast to effect of three-body

interactions

\\ ( http://arxiv.org/abs/0812.1387 , 355kb)

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arXiv:0902.4574 (*cross-listing*)

replaced with revised version Fri, 27 Feb 2009 14:11:26 GMT (413kb)

Title: Coherent state of the effective mass harmonic oscillator

Authors: Atreyee Biswas and Barnana Roy

Categories: math-ph math.MP quant-ph

Comments: 18 Pages, 5 Figures. To be published in Mod. Phys. Lett. A

\\ ( http://arxiv.org/abs/0902.4574 , 413kb)

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arXiv:cond-mat/0201217

replaced with revised version Mon, 2 Mar 2009 14:42:18 GMT (59kb)

Title: The truncated Wigner method for Bose condensed gases: limits of validity

and applications

Authors: Alice Sinatra, Carlos Lobo, Yvan Castin

Categories: cond-mat.stat-mech

Comments: 28 pages, 7 figures, typos corrected in Eqs.(85) and (91)

Journal-ref: J. Phys. B 35, 3599-3631 (2002)

\\ ( http://arxiv.org/abs/cond-mat/0201217 , 59kb)

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arXiv:0807.1433

replaced with revised version Sun, 1 Mar 2009 23:32:25 GMT (143kb)

Title: Non-Abelian magnetic monopole in a Bose-Einstein condensate

Authors: Ville Pietil\"a and Mikko M\"ott\"onen

Categories: cond-mat.other cond-mat.mes-hall

Comments: 5 pages, 1 color figure; v2 modified according to referees'

suggestions, some typos corrected; v3 minor modifications, published version

Journal-ref: Phys. Rev. Lett. 102, 080403 (2009)

\\ ( http://arxiv.org/abs/0807.1433 , 143kb)

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arXiv:0809.4419

replaced with revised version Mon, 2 Mar 2009 09:05:30 GMT (249kb)

Title: Fermionization of a strongly interacting Bose-Fermi mixture in a

one-dimensional harmonic trap

Authors: Bess Yiyuan Fang (University of Singapore), Patrizia Vignolo (INLN,

Nice, France), Christian Miniatura (University of Singapore and INLN, Nice,

France), Anna Minguzzi (LPMMC, Grenoble, France)

Categories: cond-mat.other

Comments: revised version; 8 pages, 7 figures

Journal-ref: Phys. Rev. A 79, 023623 (2009)

DOI: 10.1103/PhysRevA.79.023623

\\ ( http://arxiv.org/abs/0809.4419 , 249kb)

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arXiv:0806.3877

replaced with revised version Wed, 4 Mar 2009 09:31:36 GMT (1052kb,D)

Title: Optimizing number squeezing when splitting a mesoscopic condensate

Authors: Julian Grond, Joerg Schmiedmayer, Ulrich Hohenester

Categories: cond-mat.other

Comments: 4 pages, v3: minor changes

Journal-ref: Phys. Rev. A 79, 021603(R) (2009)

DOI: 10.1103/PhysRevA.79.021603

\\ ( http://arxiv.org/abs/0806.3877 , 1052kb)

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arXiv:0807.0572

replaced with revised version Thu, 5 Mar 2009 16:38:47 GMT (326kb)

Title: Probing the thermal atoms of a Bose gas through Raman transition

Authors: Patrick Navez

Categories: cond-mat.other

Comments: 18 pages, 6 figures, Topical Issue on Novel Quantum Phases and

Mesoscopic Physics in Quantum Gases

DOI: 10.1140/epjb/e2009-00073-y

\\ ( http://arxiv.org/abs/0807.0572 , 326kb)

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arXiv:0901.2755

replaced with revised version Thu, 5 Mar 2009 20:54:18 GMT (454kb)

Title: Scale invariant thermodynamics of a toroidally trapped Bose gas

Authors: A. S. Bradley

Categories: cond-mat.stat-mech

Comments: 10 pages, 3 figures, to appear in Phys. Rev. A, typos corrected,

references added, rewritten to emphasize generalized volume. Results

unchanged

\\ ( http://arxiv.org/abs/0901.2755 , 454kb)

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Till next time,

Matt.

-- ========================================================================= Dr M. J. Davis, Associate Professor in Physics School of Mathematics and Physics, ph : +61 7 334 69824 The University of Queensland, fax : +61 7 336 51242 Brisbane, QLD 4072, mdavis_at_physics.uq.edu.au Australia. www.physics.uq.edu.au/people/mdavis/ ========================================================================= Matt's arXiv selection: weekly summary of cold-atom papers from arXiv.org http://www.physics.uq.edu.au/people/mdavis/matts_arXiv/ ========================================================================= Legal stuff: Unless stated otherwise, this e-mail represents only the views of the sender and not the views of the University of Queensland =========================================================================Received on Tue May 19 2009 - 11:49:23 EST

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