An extended core nanocoax pillar architecture for enhanced molecular detection.

Biosensors that incorporate nanomaterials and nanofabrication techniques enable molecular detection of chemical and biological macromolecules with a high degree of specificity and ultrasensitivity. Here, we present a novel fabrication process that yields a nanostructure capable of detecting biological macromolecules. The extended core nanocoax (ECC) structure builds on a previously reported nanocoaxial-based sensor. The fabrication of the device incorporates an extended inner pillar, with controllable extension above the annulus and into the surrounding solution. This new design eliminates structural constraints inherent in the original nanocoax architecture. We also provide results demonstrating improvement in biosensing capability. Specifically, we show the capability of the new architecture to detect the B subunit of the Vibrio cholerae toxin at improved sensitivity (100 pg/ml) in comparison to optical enzyme-linked immunosorbant assay (1 ng/ml) and previously reported coaxial nanostructures (2 ng/ml).

Allospecific vocal learning by Grey parrots (Psittacus erithacus): A failure of videotaped instruction under certain conditions.

Grey parrots (Psittacus erithacus) do not acquire referential English labels when tutored with videotapes in social isolation (Pepperberg, I.M., 1994. Auk 111, 300-313) possibly because of (1) lack of social interaction to direct their attention appropriately or (2) absence of reward for an attempt at a targeted label. To test the first premise, two parrots watched videotapes with trainers who directed the birds' attention to the video monitor. Vocal praise rewarded attempts at a targeted label. To test the second premise, subjects watched videotapes in social isolation with a reward system that, in the absence of social interaction, could furnish the appropriate item after an attempt at the label. Subjects also received live interactive tutoring on a different set of object labels. Birds learned referential labels from live interactive tutors but not from videotapes. Specific aspects of live tutoring appear critical for the acquisition of referential English labels.