4,149 research outputs found
Classical and all-floating FETI methods for the simulation of arterial tissues
High-resolution and anatomically realistic computer models of biological soft
tissues play a significant role in the understanding of the function of
cardiovascular components in health and disease. However, the computational
effort to handle fine grids to resolve the geometries as well as sophisticated
tissue models is very challenging. One possibility to derive a strongly
scalable parallel solution algorithm is to consider finite element tearing and
interconnecting (FETI) methods. In this study we propose and investigate the
application of FETI methods to simulate the elastic behavior of biological soft
tissues. As one particular example we choose the artery which is - as most
other biological tissues - characterized by anisotropic and nonlinear material
properties. We compare two specific approaches of FETI methods, classical and
all-floating, and investigate the numerical behavior of different
preconditioning techniques. In comparison to classical FETI, the all-floating
approach has not only advantages concerning the implementation but in many
cases also concerning the convergence of the global iterative solution method.
This behavior is illustrated with numerical examples. We present results of
linear elastic simulations to show convergence rates, as expected from the
theory, and results from the more sophisticated nonlinear case where we apply a
well-known anisotropic model to the realistic geometry of an artery. Although
the FETI methods have a great applicability on artery simulations we will also
discuss some limitations concerning the dependence on material parameters.Comment: 29 page
Lie algebras generated by extremal elements
We study Lie algebras generated by extremal elements (i.e., elements spanning
inner ideals of L) over a field of characteristic distinct from 2. We prove
that any Lie algebra generated by a finite number of extremal elements is
finite dimensional. The minimal number of extremal generators for the Lie
algebras of type An, Bn (n>2), Cn (n>1), Dn (n>3), En (n=6,7,8), F4 and G2 are
shown to be n+1, n+1, 2n, n, 5, 5, and 4 in the respective cases. These results
are related to group theoretic ones for the corresponding Chevalley groups.Comment: 28 page
3D Bioprinted Sustained-Release Platform for Intravaginal Delivery of Probiotics
• Bacterial Vaginosis (BV) is the most prevalent vaginal infection, affecting 30% of reproductive age women in the United States and worldwide.
• BV is characterized by a shift in the vaginal microbiome from a dominance of Lactobacilli to the overgrowth of vaginal pathogens (specifically Gardnerella vaginalis).
• Some common complications include adverse pregnancy outcomes and increased risk for sexually transmitted diseases.
• Current treatment primarily involves antibiotics, but this is ineffective due to high antibiotic resistance and BV recurrence rates of 50%. Thus, a more permanent cure is sought.
• Lactobacilli probiotics are a promising alternative to antibiotics. They have shown success in reestablishing healthy flora, inhibiting pathogen growth, and reducing recurrence.
• Probiotics have been administered both orally and intravaginally, but vaginal delivery is preferred.
• Unfortunately, present vaginal dosage forms require frequent administration, thereby decreasing user adherence and efficacy.
• Only one sustained release probiotic dosage form, in the form of pod intravaginal rings, has been published to date. However this design leads to discomfort and is susceptible to biofilm formation.
• Therefore, an intravaginal probiotic delivery platform capable of sustained release and that offers women flexibility in dosage forms is necessary
Roughness gradient induced spontaneous motion of droplets on hydrophobic surfaces: A lattice Boltzmann study
The effect of a step wise change in the pillar density on the dynamics of
droplets is investigated via three-dimensional lattice Boltzmann simulations.
For the same pillar density gradient but different pillar arrangements, both
motion over the gradient zone as well as complete arrest are observed. In the
moving case, the droplet velocity scales approximately linearly with the
texture gradient. A simple model is provided reproducing the observed linear
behavior. The model also predicts a linear dependence of droplet velocity on
surface tension. This prediction is clearly confirmed via our computer
simulations for a wide range of surface tensions.Comment: 6 pages, 8 figure
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