21,346 research outputs found
Genetics of common polygenic ischaemic stroke: current understanding and future challenges.
Stroke is the third commonest cause of death and the major cause of adult neurological disability worldwide. While much is known about conventional risk factors such as hypertension, diabetes and incidence of smoking, these environmental factors only account for a proportion of stroke risk. Up to 50% of stroke risk can be attributed to genetic risk factors, although to date no single risk allele has been convincingly identified as contributing to this risk. Advances in the field of genetics, most notably genome wide association studies (GWAS), have revealed genetic risks in other cardiovascular disease and these techniques are now being applied to ischaemic stroke. This paper covers previous genetic studies in stroke including candidate gene studies, discusses the genome wide association approach, and future techniques such as next generation sequencing and the post-GWAS era. The review also considers the overlap from other cardiovascular diseases and whether findings from these may also be informative in ischaemic stroke
Electrolyte solutions at curved electrodes. I. Mesoscopic approach
Within the Poisson-Boltzmann (PB) approach electrolytes in contact with
planar, spherical, and cylindrical electrodes are analyzed systematically. The
dependences of their capacitance on the surface charge density and
the ionic strength are examined as function of the wall curvature. The
surface charge density has a strong effect on the capacitance for small
curvatures whereas for large curvatures the behavior becomes independent of
. An expansion for small curvatures gives rise to capacitance
coefficients which depend only on a single parameter, allowing for a convenient
analysis. The universal behavior at large curvatures can be captured by an
analytic expression.Comment: accepted for publication in the Journal of Chemical Physic
Surface properties of fluids of charged platelike colloids
Surface properties of mixtures of charged platelike colloids and salt in
contact with a charged planar wall are studied within density functional
theory. The particles are modeled by hard cuboids with their edges constrained
to be parallel to the Cartesian axes corresponding to the Zwanzig model and the
charges of the particles are concentrated in their centers. The density
functional applied is an extension of a recently introduced functional for
charged platelike colloids. Analytically and numerically calculated bulk and
surface phase diagrams exhibit first-order wetting for sufficiently small
macroion charges and isotropic bulk order as well as first-order drying for
sufficiently large macroion charges and nematic bulk order. The asymptotic
wetting and drying behavior is investigated by means of effective interface
potentials which turn out to be asymptotically the same as for a suitable
neutral system governed by isotropic nonretarded dispersion forces. Wetting and
drying points as well as predrying lines and the corresponding critical points
have been located numerically. A crossover from monotonic to non-monotonic
electrostatic potential profiles upon varying the surface charge density has
been observed. Due to the presence of both the Coulomb interactions and the
hard-core repulsions, the surface potential and the surface charge do not
vanish simultaneously, i.e., the point of zero charge and the isoelectric point
of the surface do not coincide.Comment: 14 pages, submitte
Electrostatic interaction between colloidal particles trapped at an electrolyte interface
The electrostatic interaction between colloidal particles trapped at the
interface between two immiscible electrolyte solutions is studied in the limit
of small inter-particle distances. Within an appropriate model exact analytic
expressions for the electrostatic potential as well as for the surface and line
interaction energies are obtained. They demonstrate that the widely used
superposition approximation, which is commonly applied to large distances
between the colloidal particles, fails qualitatively at small distances and is
quantitatively unreliable even at large distances. Our results contribute to an
improved description of the interaction between colloidal particles trapped at
fluid interfaces.Comment: Submitte
Stability of thin liquid films and sessile droplets under confinement
The stability of nonvolatile thin liquid films and of sessile droplets is
strongly affected by finite size effects. We analyze their stability within the
framework of density functional theory using the sharp kink approximation,
i.e., on the basis of an effective interface Hamiltonian. We show that finite
size effects suppress spinodal dewetting of films because it is driven by a
long-wavelength instability. Therefore nonvolatile films are stable if the
substrate area is too small. Similarly, nonvolatile droplets connected to a
wetting film become unstable if the substrate area is too large. This
instability of a nonvolatile sessile droplet turns out to be equivalent to the
instability of a volatile drop which can attain chemical equilibrium with its
vapor.Comment: 14 pages, 13 figure
Poisson-Boltzmann study of the effective electrostatic interaction between colloids at an electrolyte interface
The effective electrostatic interaction between a pair of colloids, both of
them located close to each other at an electrolyte interface, is studied by
employing the full, nonlinear Poisson-Boltzmann (PB) theory within classical
density functional theory. Using a simplified yet appropriate model, all
contributions to the effective interaction are obtained exactly, albeit
numerically. The comparison between our results and those obtained within
linearized PB theory reveals that the latter overestimates these contributions
significantly at short inter-particle separations. Whereas the surface
contributions to the linear and the nonlinear PB results differ only
quantitatively, the line contributions show qualitative differences at short
separations. Moreover, a dependence of the line contribution on the solvation
properties of the two adjacent fluids is found, which is absent within the
linear theory. Our results are expected to enrich the understanding of
effective interfacial interactions between colloids
Free Isotropic-Nematic Interfaces in Fluids of Charged Platelike Colloids
Bulk properties and free interfaces of mixtures of charged platelike colloids
and salt are studied within density-functional theory. The particles are
modeled by hard cuboids with their edges constrained to be parallel to the
artesian axes corresponding to the Zwanzig model. The charges of the particles
are concentrated in their center. The density functional is derived by
functional integration of an extension of the Debye-H\"uckel pair distribution
function with respect to the interaction potential. For sufficiently small
macroion charges, the bulk phase diagrams exhibit one isotropic and one nematic
phase separated by a first-order phase transition. With increasing platelet
charge, the isotropic and nematic binodals are shifted to higher densities. The
Donnan potential between the coexisting isotropic and nematic phases is
inferred from bulk structure calculations. Non-monotonic density and nematic
order parameter profiles are found at a free interface interpolating between
the coexisting isotropic and nematic bulk phases. Moreover, electrically
charged layers form at the free interface leading to monotonically varying
electrostatic potential profiles. Both the widths of the free interfaces and
the bulk correlation lengths are approximately given by the Debye length. For
fixed salt density, the interfacial tension decreases upon increasing the
macroion charge.Comment: 11 pages, submitted to J. Chem. Phy
Order of wetting transitions in electrolyte solutions
For wetting films in dilute electrolyte solutions close to charged walls we
present analytic expressions for their effective interface potentials. The
analysis of these expressions renders the conditions under which corresponding
wetting transitions can be first- or second-order. Within mean field theory we
consider two models, one with short- and one with long-ranged solvent-solvent
and solvent-wall interactions. The analytic results reveal in a transparent way
that wetting transitions in electrolyte solutions, which occur far away from
their critical point (i.e., the bulk correlation length is less than half of
the Debye length) are always first-order if the solvent-solvent and
solvent-wall interactions are short-ranged. In contrast, wetting transitions
close to the bulk critical point of the solvent (i.e., the bulk correlation
length is larger than the Debye length) exhibit the same wetting behavior as
the pure, i.e., salt-free, solvent. If the salt-free solvent is governed by
long-ranged solvent-solvent as well as long-ranged solvent-wall interactions
and exhibits critical wetting, adding salt can cause the occurrence of an
ion-induced first-order thin-thick transition which precedes the subsequent
continuous wetting as for the salt-free solvent.Comment: Submitte
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