Universal Single-Mode Lasing in Fully Chaotic Billiard Lasers.

By numerical simulations and experiments of fully chaotic billiard lasers, we show that single-mode lasing states are stable, whereas multi-mode lasing states are unstable when the size of the billiard is much larger than the wavelength and the external pumping power is sufficiently large. On the other hand, for integrable billiard lasers, it is shown that multi-mode lasing states are stable, whereas single-mode lasing states are unstable. These phenomena arise from the combination of two different nonlinear effects of mode-interaction due to the active lasing medium and deformation of the billiard shape. Investigations of billiard lasers with various shapes revealed that single-mode lasing is a universal phenomenon for fully chaotic billiard lasers.

Apoptosis occurs during early development of the bursa of Fabricius in chicken embryos.

The bursa of Fabricius (BF) is a unique primary lymphoid organ, and among vertebrates is unique to birds. Despite its importance to the immune systems of various avian species, little is known of the molecular mechanisms underlying early BF development. In the present study, we demonstrated that apoptosis occurs during early development of the bursa of Fabricius in chicken embryos. Initial histological analyses of BF morphogenesis in chicken embryos led to the hypothesis that formation of the bursal lumen correlates with fusion of vacuoles, which appear in the cloacal epithelial bud. Using terminal deoxynucleotidyl transferase deoxyuridine triphosphate (dUTP) nick-end labeling (TUNEL) analysis and immunostaining with an anti-cleaved (activated) caspase-3 antibody, we detected multiple apoptotic cells around these vacuoles. In further experiments, treatments with a caspase inhibitor caused abnormal bursal lumen in vivo. The present data indicate that apoptosis may play important roles in BF morphogenesis in chickens.