1,006 research outputs found
The Athena++ Adaptive Mesh Refinement Framework: Multigrid Solvers for Self-Gravity
We describe the implementation of multigrid solvers in the Athena++ adaptive
mesh refinement (AMR) framework and their application to the solution of the
Poisson equation for self-gravity. The new solvers are built on top of the AMR
hierarchy and TaskList framework of Athena++ for efficient parallelization. We
adopt a conservative formulation for the Laplacian operator that avoids
artificial accelerations at level boundaries. Periodic, fixed, and
zero-gradient boundary conditions are implemented, as well as open boundary
conditions based on a multipole expansion. Hybrid parallelization using both
MPI and OpenMP is adopted, and we present results of tests demonstrating the
accuracy and scaling of the methods. On a uniform grid we show multigrid
significantly outperforms methods based on FFTs, and requires only a small
fraction of the compute time required by the (highly optimized)
magnetohydrodynamic solver in Athena++. As a demonstration of the capabilities
of the methods, we present the results of a test calculation of magnetized
protostellar collapse on an adaptive mesh.Comment: 28 pages, 13 figures, submitted to AAS Journal
Comparative examination of subcutaneous tissue reaction to high molecular materials in medical use
Polypropylene (PP), Polyethylene (PE) and polytetra-fluoroethylene (FE) are high molecular materials in medical use. They are also used as the negative control materials for ISO 10993-6 international standard biological evaluation of medical devices. We examined tissue reactions to these materials embedded subcutaneously in the dorsal area of male ddY mice. One week and 12 weeks after embedding, the tissue surrounding the embeddingg site was removed and then histopathological examination was performed. Our results demonstrate that the basic histopathological reaction is the formation of fibrous capsule consisting of granulation tissue around the embedded materials. Based on our results, we believe that the high molecular materials such as, PP, PE and FE, can be considered for medical use as a biomaterials within the body
Histopathological examination of newly-developed adhesive silicone denture relining material
We aimed to evaluate the subcutaneous tissue reaction to a newly developed adhesive silicone denture relining material, SG, (Neo Dental Chemical Products Co., Ltd. Tokyo, Japan). We embedded the experimental material SG and another existing control material, Roeko Seal (RS), in the dorsal area of 22 male ddY mice. One week and 12 weeks after the embedding, the tissues surrounding the embedded materials were removed and a histopathological examination was performed. The results demonstrate that the basic histopathological aspects are the formation of granulation tissue and the change of the tissue to fibrous capsule over time. The results suggests that the newly-developed SG is safe as compared with the control RS, whose composition is similar
Histopathological Safety Evaluation of Newly-Developed MgO Sealer
We aimed to evaluate the subcutaneous tissue reaction to a newly-developed MgO Sealer for root canals. We injected the experimental material and three existing control materials into the dorsal area of 43 male ddY mice. One week and 12 weeks after embedding, the tissue surrounding the embedding sites was removed and histopathological examination was performed. The results demonstrate that the basic histopathological reaction is the formation of fibrous capsules consisting of granulation tissue around the experimental and control embedded materials. Based on our results, we believe that the newly-developed MgO Sealer is as safe as the existing control materials and can be considered for dental use as a root canal sealer
Lowest-energy structures of 13-atom binary clusters: Do icosahedral clusters exist in binary liquid alloys?
Although the existence of 13-atom icosahedral clusters in one-component
close-packed undercooled liquids was predicted more than half a century ago by
Frank, the existence of such icosahedral clusters is less clear in liquid
alloys. We study the lowest-energy structures of 13-atom AxB13-x Lennard-Jones
binary clusters using the modified space-fixed genetic algorithm and the
artificial Lennard-Jones potential designed by Kob and Andersen. Curiously, the
lowest-energy structures are non-icosahedral for almost all compositions. The
role played by the icosahedral cluster in a binary glass is questionable.Comment: 10 pages, 3 figure (conference paper of LAM12) to be published in J.
Non-Crystalline Solid
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