1,823 research outputs found
Large renal aneurysm successfully treated by percutaneous embolization using detachable steel coils
The definitive version is available at www.blackwell-synergy.com.ArticleInternational Journal of Urology. 13(7): 993-994 (2006)journal articl
On the second-order temperature jump coefficient of a dilute gas
We use LVDSMC simulations to calculate the second-order temperature jump
coefficient for a dilute gas whose temperature is governed by the Poisson
equation with a constant forcing term. Both the hard sphere gas and the BGK
model of the Boltzmann equation are considered. Our results show that the
temperature jump coefficient is different from the well known linear and steady
case where the temperature is governed by the homogeneous heat conduction
(Laplace) equation
Incorporating Forcing Terms in Cascaded Lattice-Boltzmann Approach by Method of Central Moments
Cascaded lattice-Boltzmann method (Cascaded-LBM) employs a new class of
collision operators aiming to improve numerical stability. It achieves this and
distinguishes from other collision operators, such as in the standard single or
multiple relaxation time approaches, by performing relaxation process due to
collisions in terms of moments shifted by the local hydrodynamic fluid
velocity, i.e. central moments, in an ascending order-by-order at different
relaxation rates. In this paper, we propose and derive source terms in the
Cascaded-LBM to represent the effect of external or internal forces on the
dynamics of fluid motion. This is essentially achieved by matching the
continuous form of the central moments of the source or forcing terms with its
discrete version. Different forms of continuous central moments of sources,
including one that is obtained from a local Maxwellian, are considered in this
regard. As a result, the forcing terms obtained in this new formulation are
Galilean invariant by construction. The method of central moments along with
the associated orthogonal properties of the moment basis completely determines
the expressions for the source terms as a function of the force and macroscopic
velocity fields. In contrast to the existing forcing schemes, it is found that
they involve higher order terms in velocity space. It is shown that the
proposed approach implies "generalization" of both local equilibrium and source
terms in the usual lattice frame of reference, which depend on the ratio of the
relaxation times of moments of different orders. An analysis by means of the
Chapman-Enskog multiscale expansion shows that the Cascaded-LBM with forcing
terms is consistent with the Navier-Stokes equations. Computational experiments
with canonical problems involving different types of forces demonstrate its
accuracy.Comment: 55 pages, 4 figure
Volumetric formulation of lattice Boltzmann models with energy conservation
We analyze a volumetric formulation of lattice Boltzmann for compressible
thermal fluid flows. The velocity set is chosen with the desired accuracy,
based on the Gauss-Hermite quadrature procedure, and tested against controlled
problems in bounded and unbounded fluids. The method allows the simulation of
thermohydrodyamical problems without the need to preserve the exact
space-filling nature of the velocity set, but still ensuring the exact
conservation laws for density, momentum and energy. Issues related to boundary
condition problems and improvements based on grid refinement are also
investigated.Comment: 8 figure
Lattice Boltzmann scheme for mixture modeling: analysis of the continuum diffusion regimes recovering Maxwell-Stefan model and incompressible Navier-Stokes equations
Knudsen Effect in a Nonequilibrium Gas
From the molecular dynamics simulation of a system of hard-core disks in
which an equilibrium cell is connected with a nonequilibrium cell, it is
confirmed that the pressure difference between two cells depends on the
direction of the heat flux. From the boundary layer analysis, the velocity
distribution function in the boundary layer is obtained. The agreement between
the theoretical result and the numerical result is fairly good.Comment: 4pages, 4figure
miRNA-based rapid differentiation of purified neurons from hPSCs advancestowards quick screening for neuronal disease phenotypes in vitro
Obtaining differentiated cells with high physiological functions by an efficient, but simple and rapid differentiation method is crucial for modeling neuronal diseases in vitro using human pluripotent stem cells (hPSCs). Currently, methods involving the transient expression of one or a couple of transcription factors have been established as techniques for inducing neuronal differentiation in a rapid, single step. It has also been reported that microRNAs can function as reprogramming effectors for directly reprogramming human dermal fibroblasts to neurons. In this study, we tested the effect of adding neuronal microRNAs, miRNA-9/9*, and miR-124 (miR-9/9*-124), for the neuronal induction method of hPSCs using Tet-On-driven expression of the Neurogenin2 gene
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