Concentration gradients are believed to play a key role in guiding axons to their appropriate targets during neural development. However, there are fundamental physical constraints on gradient detection, and these strongly limit the fidelity with which axons can respond to gradient cues. I discuss these constraints and argue they suggest that many axon guidance events in vivo cannot be explaine...

We propose a model molecular wire sensor that can detect zerovalent chromium by a strong increase in conductance when included in a metal-molecule-metal junction. An essential part of the sensor is a paracyclophane unit that binds to the metal atom. The nature and the energies of the molecular orbitals change drastically after the complex is formed, resulting in a 10- to 12-fold increase in con...

We detail here a method to integrate chemical synthesis with the formation of nanoscale electrical “sockets” to allow the in situ construction of three-component molecular wires. Reaction chemistry offers molecular materials an overwhelming amount of diversity and functionality and could provide a method for nanoscale electronics to be synthesized rather than fabricated. Though presently underu...

Molecular conductance junctions are structures in which single molecules or small groups of molecules conduct electrical current between two electrodes. In such junctions, the connection between the molecule and the electrodes greatly affects the current-voltage characteristics. Despite several experimental and theoretical advances, including the understanding of simple systems, there is still ...

The treatment of the previous paper is extended to molecular wires. Specifically, the effect of electron-vibrational interactions on the electronic transport induced by femtosecond omega+2omega laser fields along unbiased molecular nanojunctions is investigated. For this, the photoinduced vibronic dynamics of trans-polyacetylene oligomers coupled to macroscopic metallic leads is followed in a m...

We report a noise mapping strategy for the reliable identification and analysis of noise sources in molecular wire junctions. Here, different molecular wires were patterned on a gold substrate, and the current-noise map on the pattern was measured and analyzed, enabling the quantitative study of noise sources in the patterned molecular wires. The frequency spectra of the noise from the molecula...

– The influence of Gaussian laser pulses on the transport through molecular wires is investigated within a tight-binding model for spinless electrons including correlation. Motivated by the phenomenon of coherent destruction of tunneling for monochromatic laser fields, situations are studied in which the maximum amplitude of the electric field fulfills the conditions for the destructive quantum...