13,409 research outputs found
Dynamical density functional theory: phase separation in a cavity and the influence of symmetry
Consider a fluid composed of two species of particles, where the
interparticle pair potentials . On confining an
equal number of particles from each species in a cavity, one finds that the
average one body density profiles of each species are constrained to be exactly
the same due to the symmetry, when both external cavity potentials are the
same. For a binary fluid of Brownian particles interacting via repulsive
Gaussian pair potentials that exhibits phase separation, we study the dynamics
of the fluid one body density profiles on breaking the symmetry of the external
potentials, using the dynamical density functional theory of Marconi and
Tarazona [{\it J. Chem. Phys.}, {\bf 110}, 8032 (1999)]. On breaking the
symmetry we see that the fluid one body density profiles can then show the
phase separation that is present.Comment: 7 pages, 4 figures. Accepted for the proceedings of the Liquid Matter
conference 2005, to be publication in J. Phys.: Condens. Matte
Constraints on Dimensional Warped Spaces
In order to investigate the phenomenological implications of allowing gauge
fields to propagate in warped spaces of more than five dimensions, we consider
a toy model of a space warped by the presence of a anisotropic bulk
cosmological constant. After solving the Einstein equation, three classes of
solutions are found, those in which the additional () dimensions are
growing, shrinking or remaining constant. It is found that gauge fields
propagating in these spaces have a significantly different Kaluza Klein (KK)
mass spectrum and couplings from that of the Randall and Sundrum model. This
leads to a greatly reduced lower bound on the KK scale, arising from
electroweak constraints, for spaces growing towards the IR brane.Comment: 6 pages, 5 figures PASCOS2010 International Symposium proceedin
Microscopic theory of solvent mediated long range forces: influence of wetting
We show that a general density functional approach for calculating the force
between two big particles immersed in a solvent of smaller ones can describe
systems that exhibit fluid-fluid phase separation: the theory captures effects
of strong adsorption (wetting) and of critical fluctuations in the solvent. We
illustrate the approach for the Gaussian core model, a simple model of a
polymer mixture in solution and find extremely attractive, long ranged solvent
mediated potentials between the big particles for state points lying close to
the binodal, on the side where the solvent is poor in the species which is
favoured by the big particles.Comment: 7 pages, 3 figures, submitted to Europhysics Letter
New genus of primitive wombat (Vombatidae, Marsupialia) from Miocene deposits in the Riversleigh World Heritage Area (Queensland, Australia)
Copyright Palaeontological Association, March 2015.
This is an open access article, available to all readers online, published under a creative commons licensing (https://creativecommons.org/licenses/by/4.0/)
Dynamical density functional theory analysis of the laning instability in sheared soft matter
Using dynamical density functional theory (DDFT) methods we investigate the
laning instability of a sheared colloidal suspension. The nonequilibrium
ordering at the laning transition is driven by non-affine particle motion
arising from interparticle interactions. Starting from a DDFT which
incorporates the non-affine motion, we perform a linear stability analysis that
enables identification of the regions of parameter space where lanes form. We
illustrate our general approach by applying it to a simple one-component fluid
of soft penetrable particles
Legal medical consideration of alzheimer’s disease patients’ dysgraphia and cognitive dysfunction: a 6 month follow up
Background: The purpose of this study was to investigate the ability of Alzheimer’s disease
(AD) patients to express intentions and desires, and their decision-making capacity. This study
examines the findings from a 6-month follow-up of our previous results in which 30 patients
participated.
Materials and methods: The patient’s cognition was examined by conducting the tests of 14
questions and letter-writing ability over a period of 19 days, and it was repeated after 6 months.
The difference between these two cognitive measures (PQ1 before–PQ2 before), tested previously
and later the writing test, was designated DΔ before. The test was repeated after 6 months,
and PQ1 after–PQ2 after was designated DΔ after.
Results: Several markedly strong relationships between dysgraphia and other measures of
cognitive performance in AD patients were observed. The most aged patients (over 86 years),
despite less frequency, maintain the cognitive capacity manifested in the graphic expressions.
A document, written by an AD patient presents an honest expression of the patient’s intention
if that document is legible, clear, and comprehensive.
Conclusion: The identification of impairment/deficits in writing and cognition during different
phases of AD may facilitate the understanding of disease progression and identify the occasions
during which the patient may be considered sufficiently lucid to make decisions.
Keywords: cognition, intentions, unfit to plead, consen
Large bias-dependent magnetoresistance in all-oxide magnetic tunnel junctions with a ferroelectric barrier
All-oxide magnetic tunnel junctions (MTJs) incorporating functional materials
as insulating barriers have the potential of becoming the founding technology
for novel multi-functional devices. We investigate, by first-principles density
functional theory, the bias-dependent transport properties of an all-oxide
SrRuO3/BaTiO3/SrRuO3 MTJ. This incorporates a BaTiO3 barrier which can be found
either in a non-ferroic or in a ferroelectric state. In such an MTJ not only
can the tunneling magnetoresistance reach enormous values, but also, for
certain voltages, its sign can be changed by altering the barrier electric
state. These findings pave the way for a new generation of
electrically-controlled magnetic sensors.Comment: 4 pages, 5 figure
Solvent mediated interactions close to fluid-fluid phase separation: microscopic treatment of bridging in a soft core fluid
Using density functional theory we calculate the density profiles of a binary
solvent adsorbed around a pair of big solute particles. All species interact
via repulsive Gaussian potentials. The solvent exhibits fluid-fluid phase
separation and for thermodynamic states near to coexistence the big particles
can be surrounded by a thick adsorbed `wetting' film of the coexisting solvent
phase. On reducing the separation between the two big particles we find there
can be a `bridging' transition as the wetting films join to form a fluid
bridge. The potential between the two big particles becomes long ranged and
strongly attractive in the bridged configuration. Within our mean-field
treatment the bridging transition results in a discontinuity in the solvent
mediated force. We demonstrate that accounting for the phenomenon of bridging
requires the presence of a non-zero bridge function in the correlations between
the solute particles when our model fluid is described within a full mixture
theory based upon the Ornstein-Zernike equations.Comment: 28 pages, 8 figure
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