The roles of ram-pressure stripping and minor mergers in evolution of galaxies

We investigate environmental effects on evolution of bright cluster galaxies in a Lambda-dominated cold dark matter universe using a combination of dissipationless N-body simulations and a semi-analytic galaxy formation model. We incorporate effects of ram-pressure stripping (RPS) and minor merger-induced small starburst (minor burst) into our model. By considering minor burst, observed morphology-radius relation is successfully reproduced. When we do not consider minor burst, the RPS hardly increases the intermediate B/T population. In addition, the RPS and minor burst are not important for colours or star formation rates of galaxies in the cluster core if star formation time-scale is properly chosen, because the star formation is sufficiently suppressed by consumption of the cold gas. We also find that SF in bulge-dominated galaxies is mainly terminated by starburst induced by major mergers in all environments.Comment: To appear in the proceedings of IAU colloq. No. 195, "Outskirts of Galaxy Clusters: intense life in the suburbs", Torino, 12-16 March 2004, 5 pages, 2 figures, uses IAU macr

Spin-Chirality Separation and S_3-Symmetry Breakings in the Magnetization Plateau of the Quantum Spin Tube

We study the magnetization plateau state of the three-leg spin-1/2 tube in the strong rung coupling region, where S_3-symmetry breakings and low-energy chirality degree of freedom play crucial roles. On the basis of the effective chirality model and density matrix renormalization group, we clarify that, as the leg coupling increases, the chirality liquid with gapless non-magnetic excitations, the spin imbalance phase and the vector-spin-chirality ordered phase emerge without closing the plateau spin gap. The relevance of these results to experiments is also discussed.Comment: 6 pages, 6 figures, detailed results of the spin imbalance state are adde

Numerical analysis of the eutectic melting and relocation of the b4c control rod materials by the MPFI-MPS method

Eutectic melting and subsequent relocation of the boron-carbide (B4C) control rod materials were simulated by a particle method. In the past, it was difficult to simulate the eutectic melting by a particle method because the melting starts at the interface between two different materials, which leads to the instability of the particle motion due to the small amount of fluid particles and lack of the thermodynamic consistency of the particle system. Thus, the Moving Particle Full Implicit (MPFI)-Moving Particle Semi-implicit (MPS) method was developed and introduced in the current study. Specifically, the MPFI method was introduced for the momentum transfer calculation, and the MPS method was introduced for the heat and mass transfer calculation. The MPFIMPS method realized the simulation of the eutectic melting and subsequent relocation behaviour