Quadrupole-scissors modes and nonlinear mode coupling in trapped two-component Bose-Einstein condensates

We theoretically investigate quadrupolar collective excitations in two-component Bose-Einstein condensates and their nonlinear dynamics associated with harmonic generation and mode coupling. Under the Thomas-Fermi approximation and the quadratic polynomial ansatz for density fluctuations, the linear analysis of the superfluid hydrodynamic equations predicts excitation frequencies of three normal modes constituted from monopole and quadrupole oscillations, and those of three scissors modes. We obtain analytically the resonance conditions for the second harmonic generation in terms of the trap aspect ratio and the strength of intercomponent interaction. The numerical simulation of the coupled Gross-Pitaevskii equations vindicates the validity of the analytical results and reveals the dynamics of the second harmonic generation and nonlinear mode coupling that lead to nonlinear oscillations of the condensate with damping and recurrence reminiscent of the Fermi-Pasta-Ulam problem.Comment: 10 pages, 5 figures, revtex

True Taxpayer Burden of Bank Restructuring

We formalize the taxpayer burden implied by various bank restructuring plans. Even assuming minimal frictions, in spirit of Modigliani and Miller (1958), when debt contracts cannot be changed, transfers from the taxpayer (in a Net Present Value sense) are necessary. Debt holders benefit from a lower default probability and a higher recovery given default. Absent government transfers, their gains imply a decrease in equity value. Shareholders will therefore oppose the restructuring unless they receive transfers from taxpayers. The taxpayer burden consists of the NPV of inflows and outflows of cash needed to persuade shareholders (or bank managers) to accept a change in capital structure. The government’s intervention aims at preventing systemic effects from a default of an important bank, and thus targets a default rate. Due to different implied recovery rates given default, the required transfer amounts vary across restructuring plans that achieve the same target default rate. In this regard, asset sales require more transfers than recapitalization or asset guarantees, because asset sales support a higher recovery rate

Competition of resonant and nonresonant paths in resonance-enhanced two-photon single ionization of He by an ultrashort extreme-ultraviolet pulse

We theoretically study the pulse-width dependence of the photoelectron angular distribution (PAD) from the resonance-enhanced two-photon single ionization of He by femtosecond ($\lesssim 20$ fs) extreme-ultraviolet pulses, based on the time-dependent perturbation theory and simulations with the full time-dependent Schr\"odinger equation. In particular, we focus on the competition between resonant and nonresonant ionization paths, which leads to the relative phase $\delta$ between the $S$ and $D$ wave packets distinct from the corresponding scattering phase shift difference. When the spectrally broadened pulse is resonant with an excited level, the competition varies with pulse width, and, therefore, $\delta$ and the PAD also change with it. On the other hand, when the Rydberg manifold is excited, $\delta$ and the PAD do not much vary with the pulse width, except for the very short pulse regime.Comment: 5 pages, 5 figures, 1 tabl

Lung Separation in the Morbidly Obese Patient

Lung separation techniques in the morbidly obese patient undergoing thoracic or esophageal surgery may be at risk of complications during airway management. Access to the airway in the obese patient can be a challenge because they have altered airway anatomy, including a short and redundant neck, limited neck extension and accumulation of fat deposition in the pharyngeal wall contributing to difficult laryngoscopy. Securing the airway is the first priority in these patients followed by appropriate techniques for lung separation with the use of a single-lumen endotracheal tube and a bronchial blocker or another alternative is with the use of a double-lumen endotracheal tube. This review is focused on the use of lung isolation devices in the obese patient. The recommendations are based upon scientific evidence, case reports or personal experience. Fiberoptic bronchoscopy must be used to place and confirm proper placement of a single-lumen endotracheal tube, bronchial blocker or double-lumen endotracheal tube