Persistent current formation in a high-temperature Bose-Einstein condensate: an experimental test for c-field theory

Experimental stirring of a toroidally trapped Bose-Einstein condensate at high temperature generates a disordered array of quantum vortices that decays via thermal dissipation to form a macroscopic persistent current [T. W. Neely em et al. arXiv:1204.1102 (2012)]. We perform 3D numerical simulations of the experimental sequence within the Stochastic Projected Gross-Pitaevskii equation using ab initio determined reservoir parameters. We find that both damping and noise are essential for describing the dynamics of the high-temperature Bose field. The theory gives a quantitative account of the formation of a persistent current, with no fitted parameters.Comment: v2: 7 pages, 3 figures, new experimental data and numerical simulation

Suppression of Kelvon-induced decay of quantized vortices in oblate Bose-Einstein Condensates

We study the Kelvin mode excitations on a vortex line in a three-dimensional trapped Bose-Einstein condensate at finite temperature. Our stochastic Gross-Pitaevskii simulations show that the activation of these modes can be suppressed by tightening the confinement along the direction of the vortex line, leading to a strong suppression in the vortex decay rate as the system enters a regime of two-dimensional vortex dynamics. As the system approaches the condensation transition temperature we find that the vortex decay rate is strongly sensitive to dimensionality and temperature, observing a large enhancement for quasi-two-dimensional traps. Three-dimensional simulations of the recent vortex dipole decay experiment of Neely et al. [Phys. Rev. Lett. 104, 160401 (2010)] confirm two-dimensional vortex dynamics, and predict a dipole lifetime consistent with experimental observations and suppression of Kelvon-induced vortex decay in highly oblate condensates.Comment: 8 pages, 8 figure

Control of surface plasmon resonances in dielectrically coated proximate gold nanoparticles immobilized on a substrate

We present experimental and theoretical results for the changes in the optical-plasmon resonance of gold-nanoparticle dimers immobilized on a surface when coated with an organic dielectric material. The plasmon band of a nanoparticle dimer shifts to a higher wavelength when the distance between neighboring particles is decreased, and a well-separated second peak appears. This phenomenon is called cross-talk. We find that an organic coating lets cross-talk start at larger separation distances than for uncoated dimers by bridging the gap between immobilized nanoparticles (creating optical clusters). We study this optical clustering effect as a function of the polarization of the applied light, of the inter-particle distance, of the surrounding environment, and of the optical properties of the coating layer. Theoretical discrete-dipole approximation calculations support the experimental absorption spectroscopy results of gold nanoparticles on glass substrates and on optical waveguides

Preliminary Evaluation of a Laparoscopic Common Bile Duct Simulator for Pediatric Surgical Education

Purpose: Laparoscopic common bile duct exploration (LCBDE) decreases overall costs and length of stay in patients with choledocolithiasis. However, utilization of LCBDE remains low. We sought to evaluate a previously developed general surgery LCBDE simulator among a cohort of pediatric surgical trainees. The study purpose was to evaluate the content validity of an LCBDE simulator to support or refute its use in pediatric surgery education. Materials and Methods: After IRB exempt determination, 30 participants performed a transcystic LCBDE using a previously developed simulator and evaluated the simulator using a self-reported 28-item instrument. The instrument consisted of two primary domains (Quality and Ability to Perform) that were rated using twenty-five 4-point rating scales and one 4-point global rating scale. Validity evidence relevant to test content was evaluated using a many-facet Rasch model. Interitem consistency was estimated using Cronbach's alpha. P?Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/140153/1/lap.2016.0248.pd