Multipeak Kondo effect in one- and two-electron quantum dots.

We have fabricated a few-electron quantum dot that can be tuned down to zero electrons while maintaining strong coupling to the leads. Using a nearby quantum point contact as a charge sensor, we can determine the absolute number of electrons in the quantum dot. We find several sharp peaks in the differential conductance, occurring at both zero and finite source-drain bias, for the one- and two-electron quantum dot. We attribute the peaks at finite bias to a Kondo effect through excited states of the quantum dot and investigate the magnetic field dependence of these Kondo resonances.

Ge/Si nanowire mesoscopic Josephson junctions.

The controlled growth of nanowires (NWs) with dimensions comparable to the Fermi wavelengths of the charge carriers allows fundamental investigations of quantum confinement phenomena. Here, we present studies of proximity-induced superconductivity in undoped Ge/Si core/shell NW heterostructures contacted by superconducting leads. By using a top gate electrode to modulate the carrier density in the NW, the critical supercurrent can be tuned from zero to greater than 100 nA. Furthermore, discrete sub-bands form in the NW due to confinement in the radial direction, which results in stepwise increases in the critical current as a function of gate voltage. Transport measurements on these superconductor-NW-superconductor devices reveal high-order (n = 25) resonant multiple Andreev reflections, indicating that the NW channel is smooth and the charge transport is highly coherent. The ability to create and control coherent superconducting ordered states in semiconductor-superconductor hybrid nanostructures allows for new opportunities in the study of fundamental low-dimensional superconductivity.

Proposed technique for evaluation of endotracheal tube fixation and comparison of four fixation methods.

BACKGROUND: The fixation of an endotracheal tube must be rapid in conditions involving numerous casualties, such as a chemical warfare (CW) situation. The tube also should be fixed and strong to prevent unplanned extubations. METHODS: We developed a technique for the evaluation of fixation methods. This technique was used to evaluate four methods. Three commercial fixators were compared with the fixation method used today in the Israeli Defense Forces (IDF) and commonly used in different out-of-hospital settings. The exercises were performed on adult intubation mannequins with and without CW protective gear. The fixations were timed, and their quality was evaluated by the participants and inspectors. RESULTS: The time score for the method used today in the IDF was significantly higher compared with the commercial fixation methods. The quality scores for the Thomas fixator and the IDF method were significantly higher than for the fixators by VBM and Rusch. The CW protective gear significantly prolonged the time but did not affect the quality of the fixation. CONCLUSIONS: With this technique, a good estimation of the time and quality of fixation can be achieved.