Rounding of aggregates of biological cells: Experiments and simulations

The influence of surface tension and size on rounding of cell aggregates are studied using chick embryonic cells and numerical simulations based on the cellular Potts model. Our results show exponential relaxation in both cases as verified in previous studies using 2D Hydra cell aggregates. The relaxation time decreases with higher surface tension as expected from hydrodynamics laws. However, it increases faster than linearly with aggregate size. The results provide an additional support to the validity of the cellular Potts model for non-equilibrium situations and indicate that aggregate shape relaxation is not governed by the hydrodynamics of viscous liquids

Internal friction measurement in high purity tungsten single crystal

Internal friction peaks observed after small deformation in high purity tungsten single crystals between liquid helium temperature and 800 K in the frequency range 30-50 KHz, are studied as a function of orientation. An orientation effect is observed in the internal friction spectra due to the creation of internal stresses. The elementary processes related to these peaks are discussed in terms of kink generation and geometric kink motion on screw and edge dislocations in an internal stress field

Circumstellar radio molecular lines

Radio molecular lines appear to be useful probes into the stellar environment. Silicon oxide masers provide information on the physical conditions in the immediate vicinity of the stellar photosphere. Valuable information on the physics operating in the envelope of IRC + 10216 was recently obtained by high sensitivity observations and detailed theoretical analyses. Infrared speckle interferometry in the molecular lines and in the continuum is helpful in the investigation of the inner region of the envelope. These techniques are discussed in terms of late-type star mass loss

Do asset price fluctuations constitute a risk to growth in the major industrialised countries?

Asset price fluctuations give grounds for concern in the major industrialised countries. But to what extent do they affect economic growth? The answer to this question partly depends on households’ levels of debt and the structure of their financial wealth. We shall first summarise the different wealth effect estimates. This analysis shows that the impact of asset price fluctuations is more pronounced in the United States and the United Kingdom than in euro area countries. Asset price fluctuations in the United States appear to have an even greater impact on euro area growth than changes in household wealth within the euro area. Overall, outside of the United States and the United Kingdom, wealth effects are fairly limited, despite the existence of spillover effects transmitted through international trade and/or financial markets. Furthermore, these findings seem to be consistent with those obtained using other quantitative approaches that analyse the co-movements between business and financial cycles. They also conclude that, apart from in the United States, a high degree of dependence between economic growth and asset price fluctuations in the short term cannot be identified. We shall then provide an international comparison of the financial position of households (United States, Japan, United Kingdom, Germany, France and Italy). This analysis points to a certain degree of heterogeneity. In particular, the financial vulnerability of US and UK households, which have a larger appetite for debt and risky assets, is greater than that of households of the major euro area countries. In this context, it is not surprising that the shocks affecting asset prices have a more marked effect on household consumption and growth in the United States and the United Kingdom than in the major euro area countries or in Japan.

Recent Developments in Maser Theory

This review covers selected developments in maser theory since the previous meeting, "Cosmic Masers: From Proto-Stars to Black Holes" (Migenes & Reid 2002). Topics included are time variability of fundamental constants, pumping of OH megamasers and indicators for differentiating disks from bi-directional outflows.Comment: Review presented at IAU symposium 242, "Astrophysical Masers and their Environments