21 research outputs found
Cooling of suspended nanostructures with tunnel junctions
We have investigated electronic cooling of suspended nanowires with SINIS
tunnel junction coolers. The suspended samples consist of a free standing
nanowire suspended by four narrow ( 200 nm) bridges. We have compared two
different cooler designs for cooling the suspended nanowire. We demonstrate
that cooling of the nanowire is possible with a proper SINIS cooler design
Strain sensing with sub-micron sized Al-AlOx-Al tunnel junctions
We demonstrate a local strain sensing method for nanostructures based on
metallic Al tunnel junctions with AlOx barriers. The junctions were fabricated
on top of a thin silicon nitride membrane, which was actuated with an AFM tip
attached to a stiff cantilever. A large relative change in the tunneling
resistance in response to the applied strain (gauge factor) was observed, up to
a value 37. This facilitates local static strain variation measurements down to
~10^{-7}.Comment: 4 pages, 3 figure
Positive Selection in East Asians for an EDAR Allele that Enhances NF-κB Activation
Genome-wide scans for positive selection in humans provide a promising approach to establish links between genetic variants and adaptive phenotypes. From this approach, lists of hundreds of candidate genomic regions for positive selection have been assembled. These candidate regions are expected to contain variants that contribute to adaptive phenotypes, but few of these regions have been associated with phenotypic effects. Here we present evidence that a derived nonsynonymous substitution (370A) in EDAR, a gene involved in ectodermal development, was driven to high frequency in East Asia by positive selection prior to 10,000 years ago. With an in vitro transfection assay, we demonstrate that 370A enhances NF-κB activity. Our results suggest that 370A is a positively selected functional genetic variant that underlies an adaptive human phenotype