Endovascular Treatment of a Migrated Superior Vena Cava Stent in the Right Atrium.

A 42-year-old female with end-stage chronic kidney disease, who was on maintenance hemodialysis for the last 3 years, presented with facial and upper-limb swelling of 2-month duration. A computed tomography (CT) scan confirmed significant stenosis of the superior vena cava (SVC). Following discussion in a multidisciplinary meeting, it was proposed to perform a repeat endovascular intervention to relieve the SVC obstruction and manage the migrated stent.

Current crowding mediated large contact noise in graphene field-effect transistors.

The impact of the intrinsic time-dependent fluctuations in the electrical resistance at the graphene-metal interface or the contact noise, on the performance of graphene field-effect transistors, can be as adverse as the contact resistance itself, but remains largely unexplored. Here we have investigated the contact noise in graphene field-effect transistors of varying device geometry and contact configuration, with carrier mobility ranging from 5,000 to 80,000 cm2 V-1 s-1. Our phenomenological model for contact noise because of current crowding in purely two-dimensional conductors confirms that the contacts dominate the measured resistance noise in all graphene field-effect transistors in the two-probe or invasive four-probe configurations, and surprisingly, also in nearly noninvasive four-probe (Hall bar) configuration in the high-mobility devices. The microscopic origin of contact noise is directly linked to the fluctuating electrostatic environment of the metal-channel interface, which could be generic to two-dimensional material-based electronic devices.