Nonlinear dynamics and band transport in a superlattice driven by a plane wave.

A quantum particle transport induced in a spatially periodic potential by a propagating plane wave has a number of important implications in a range of topical physical systems. Examples include acoustically driven semiconductor superlattices and cold atoms in an optical crystal. Here we apply a kinetic description of the directed transport in a superlattice beyond standard linear approximation, and utilize exact path-integral solutions of the semiclassical transport equation. We show that the particle drift and average velocities have nonmonotonic dependence on the wave amplitude with several prominent extrema. Such nontrivial kinetic behavior is related to global bifurcations developing with an increase of the wave amplitude. They cause dramatic transformations of the system phase space and lead to changes of the transport regime. We describe different types of phase trajectories contributing to the directed transport and analyze their spectral content.

Apoptosis time course in the limbic system after myocardial infarction in the rat.

Apoptosis is known to occur in the limbic system after myocardial infarction (MI) in the rat. Our study was designed to evaluate the time course dynamics of this phenomenon in limbic areas. Apoptosis, i.e., caspase-3 activity and the number of terminal dUTP nick-end labelling-positive cells, as well as brain-derived neurotrophic factor (BDNF) were quantitated in sham-operated controls and MI rats 1, 2 and 7 days after surgery. Both apoptosis parameters were increased throughout, although in different structures: the CA1 region of the hippocampus and the medial amygdala at day 1, the CA1 region of the hippocampus and the lateral amygdala at day 2, and the frontal cortex at day 7. At day 2, BDNF was decreased in the prefrontal cortex and medial amygdala, whereas it was elevated in the dentate gyrus of the hippocampus; at day 7, BDNF was reduced in the frontal cortex and posterior hypothalamus but was augmented in the medial amygdala. These data indicate that post-MI apoptosis in the limbic system is a dynamic process occurring mainly in the hippocampus and amygdala during the first days after MI. The fact that BDNF was increased as early as 2 days after MI suggests that neurogenesis can occur rapidly in selected limbic regions after MI.

Growth retardation, distinct oriental-like facies, glaucoma, brachydactyly, ventricular septal defect and speech disorder. An unknown entity.

A caucasian boy with distinct oriental-like facies, short stature, brachydactyly, congenital ventricular septal defect, glaucoma, and speech disorder is reported. Routine laboratory tests, karyotype, and hormonal profile (IGF 1, growth hormone during provocative testing, thyroid hormones, prolactin, gonadotrophins) were normal. Radiologic skeletal survey did not disclose any abnormality. Both parents were apparently normal, but short in stature.