Regional security frameworks in Israel

Comunicação proferida pelo Embaixador Oded Eran, no IDN no dia 23 de Fevereiro de 2010, no âmbito do ciclo de conferências intitulado Visões Globais para a Defesa

Feasible Nanometric Magnetoresistance Devices

The electrical conductance through a ring is sensitive to the threading magnetic flux. It contains a component that is periodic with an Aharonov-Bohm (AB) period equal to the quantum flux. In molecular/atomic loops on the nanometer scale, encircling very small areas, the AB period involves unrealistically huge magnetic fields. We show that despite this, moderate magnetic fields can have a strong impact on the conductance. By controlling the lifetime of the conduction electron through a pre-selected single state that is well separated from other states due to the quantum confinement effect, we demonstrate that magnetic fields comparable to one Tesla can be used to switch a nanometric AB device. Using atomistic electronic structure calculations, we show that such effects can be expected for loops composed of monovalent metal atoms (quantum corals). Our findings suggest that future fabrication of nanometric magnetoresistance devices is feasible.Comment: 8 pages, 4 figure

Magnetoresistance Devices Based on Single Walled Carbon Nanotubes

We demonstrate the physical principles for the construction of a nanometer sized magnetoresistance device based on the Aharonov-Bohm effect. The proposed device is made of a short single-walled carbon nanotube (SWCNT) placed on a substrate and coupled to a tip. We consider conductance due to motion of electrons along the circumference of the tube (as opposed to motion parallel to its axis). We find that the circumference conductance is sensitive to magnetic fields threading the SWCNT due to the Aharonov-Bohm effect, and show that by retracting the tip, so that its coupling to the SWCNT is reduced, very high sensitivity to the threading magnetic field develops. This is due to the formation of a narrow resonance through which the tunneling current flows. Using a bias potential the resonance can be shifted to low magnetic fields, allowing the control of conductance with magnetic fields of the order of 1 Tesla.Comment: 4 pages, 3 figure

Periodic negative differential conductance in a single metallic nano-cage

We report a bi-polar multiple periodic negative differential conductance (NDC) effect on a single cage-shaped Ru nanoparticle measured using scanning tunneling spectroscopy. This phenomenon is assigned to the unique multiply-connected cage architecture providing two (or more) defined routes for charge flow through the cage. This, in turn, promotes a self- gating effect, where electron charging of one route affects charge transport along a neighboring channel, yielding a series of periodic NDC peaks. This picture is established and analyzed here by a theoretical model

Constructing Spin Interference Devices from Nanometric Rings

The study of nanospintronic devices utilizing coherent transport through molecular scale multiply-connected geometries in the presence of moderate magnetic fields is presented. It is shown how two types of simple devices, spin filters and spin splitters (or Stern-Gerlach devices) may be constructed from molecular nanometric rings utilizing the Aharonov-Bohm effect. The current is calculated within a single electron approximation and within a many-body master equation approach where charging effects are accounted for in the Coulomb Blockade regime. We provide rules and tools to develop and analyze efficient spintronic devices based on nanometric interferometers.Comment: 16 pages, 8 figures, submitted to Phys. Rev.

miR126-5p Downregulation Facilitates Axon Degeneration and NMJ Disruption via a Non-Cell-Autonomous Mechanism in ALS.

Axon degeneration and disruption of neuromuscular junctions (NMJs) are key events in amyotrophic lateral sclerosis (ALS) pathology. Although the disease\u27s etiology is not fully understood, it is thought to involve a non-cell-autonomous mechanism and alterations in RNA metabolism. Here, we identified reduced levels of miR126-5p in presymptomatic ALS male mice models, and an increase in its targets: axon destabilizing Type 3 Semaphorins and their coreceptor Neuropilins. Using compartmentalize