Nondirected axonal growth on basal lamina from avian embryonic neural retina

The vitreous surface of the embryonic avian retinal neuroepithelium was isolated by mechanical disruption of the retina mounted between 2 adhesive substrata. The 200-micron-thick sheath covered an area of up to 1 cm2 and consisted of the vitreal basal lamina with a lamina densa, 2 laminae rarae, and a carpet of ventricular cell endfeet on top of the lamina. The vitreal endfeet were removed by detergent treatment and an extracellular basal lamina was obtained. The laminae were further characterized by immunohistochemistry and immunoblotting. A 190 kDa laminin protein was detected in laminae with and without vitreal endfeet, whereas the membrane-bound neural cell adhesion molecule (N- CAM) was detectable only on the endfeet of the ventricular cells and was absent in the detergent-treated basal laminae. Neither immunoblotting nor immunostaining revealed fibronectin in these preparations. Explants of retina, sensory ganglia, and cerebellum from chick, quail, and mouse were cultured on the basal lamina as a substratum. In all cases axonal outgrowth was excellent, with a growth rate similar to that in situ. Outgrowing axons from sensory ganglia and cerebellar explants were accompanied by migratory cells, which, in the case of sensory ganglia, were flat cells and, in the case of cerebellar explants, resembled granular neurons. Optic axons grew on the laminae in an asymmetric, explant-inherent pattern specific for the position of origin of the explant. On detergent-treated basal laminae, as well as on laminin, the retinal axons grew in a clockwise orientation. This axonal growth pattern was specific for retinal tissue and was not observed with axons from other neural explants. In spite of the excellent substrate properties provided by the substratum, cues for growing axons (toward or away from the optic disk) were not detectable in the basal lamina preparations

Charge carrier correlation in the electron-doped t-J model

We study the t-t'-t''-J model with parameters chosen to model an electron-doped high temperature superconductor. The model with one, two and four charge carriers is solved on a 32-site lattice using exact diagonalization. Our results demonstrate that at doping levels up to x=0.125 the model possesses robust antiferromagnetic correlation. When doped with one charge carrier, the ground state has momenta (\pm\pi,0) and (0,\pm\pi). On further doping, charge carriers are unbound and the momentum distribution function can be constructed from that of the single-carrier ground state. The Fermi surface resembles that of small pockets at single charge carrier ground state momenta, which is the expected result in a lightly doped antiferromagnet. This feature persists upon doping up to the largest doping level we achieved. We therefore do not observe the Fermi surface changing shape at doping levels up to 0.125

Quantum-optical influences in optoelectronics - an introduction

This focused review discusses the increasing importance of quantum optics in the physics and engineering of optoelectronic components. Two influences relating to cavity quantum electrodynamics are presented. One involves the development of low threshold lasers, when the channeling of spontaneous emission into the lasing mode becomes so efficient that the concept of lasing needs revisiting. The second involves the quieting of photon statistics to produce single-photon sources for applications such as quantum information processing. An experimental platform, consisting of quantum-dot gain media inside micro- and nanocavities, is used to illustrate these influences of the quantum mechanical aspect of radiation. An overview is also given on cavity quantum electrodynamics models that may be applied to analyze experiments or design devices.EC/FP7/615613/EU/External Quantum Control of Photonic Semiconductor Nanostructures/EXQUISIT

The first passage problem for diffusion through a cylindrical pore with sticky walls

We calculate the first passage time distribution for diffusion through a cylindrical pore with sticky walls. A particle diffusively explores the interior of the pore through a series of binding and unbinding events with the cylinder wall. Through a diagrammatic expansion we obtain first passage time statistics for the particle's exit from the pore. Connections between the model and nucleocytoplasmic transport in cells are discussed.Comment: v2: 13 pages, 6 figures, substantial revision