LES of physiological pulsatile flow in a model arterial stenosis

Physiological pulsatile flow in a 3D model of arterial stenosisis investigated by applying Large Eddy Simulation(LES)technique. The computational domain has been chosen is as imple channel with a biological type stenosis formed eccentrically on the top wall. The physiological pulsation is generated at the inlet of the model using the fourth harmonic of the Fourier series of the physiological pressure pulse. The flow Reynolds numbers which are typical of those found in human large artery are chosen in the present work. Transitions to turbulent of the pulsatile flow in the post stenosis are examined through the various numerical results and explained physically along with the relevant medical concerns

Chemical evolution of low mass disc galaxies

We show that the multiphase chemical evolution model reproduces the correlations obtained along the spiral sequence, dwarf galaxies included. However the apparent spatial chemical uniformity observed in some irregular galaxies cannot be reproduced with it. An evolutionary model has been developed and tested to explain flat gradients. Preliminary results, obtained with a new code including supernova winds and radial flows, suggest that radial flows are probably responsably for this uniformityComment: 5 pages,5 figures, to be published in the proceedings of the ESO "Chemical Evolution from Zero to High Redshift" workshop, Eds. M.Rosa and J.R. Walsh (Springer-Verlag

Radial distributions of spectral absorption indices in spiral disks

We present a grid of 440 spectro-photometric models for simulating spiral and irregular galaxies. They have been consistently calculated with evolutionary synthesis models which use as input the information proceeding from chemical evolution models. The model predictions are spectral energy distributions, brightness and color profiles and radial distributions of spectral absorption stellar indices which are in agreement with observations.Comment: 2 pages, 1 fig, contribution to IAU 241 Symp. Stellar Populations as buildinng blocks of Galaxie

Transitive Triangle Tilings in Oriented Graphs

In this paper, we prove an analogue of Corr\'adi and Hajnal's classical theorem. There exists $n_0$ such that for every $n \in 3\mathbb{Z}$ when $n \ge n_0$ the following holds. If $G$ is an oriented graph on $n$ vertices and every vertex has both indegree and outdegree at least $7n/18$, then $G$ contains a perfect transitive triangle tiling, which is a collection of vertex-disjoint transitive triangles covering every vertex of $G$. This result is best possible, as, for every $n \in 3\mathbb{Z}$, there exists an oriented graph $G$ on $n$ vertices without a perfect transitive triangle tiling in which every vertex has both indegree and outdegree at least $\lceil 7n/18\rceil - 1.$Comment: To appear in Journal of Combinatorial Theory, Series B (JCTB