2,427 research outputs found
Year-end seasonality in one-month LIBOR derivatives
We examine the markets for one-month LIBOR futures contracts and options on those futures for a year-end price effect consistent with the previously identified year-end rate increase in one-month LIBOR. The cash market rate increase appears in forward rates and derivative prices, which allows the derivatives to properly hedge year-end interest rate risk. However, while the year-end effect appears in the derivative contract, these derivative contracts provide biased forecasts of both future interest rates and their volatility. The bias appears to be different at year's end for the LIBOR futures contract, but not for the options contract. The information in the derivatives almost always subsumes simple benchmark forecasts. ; Earlier title: Seasonality in one-month LIBOR derivativesEconometrics ; Monetary policy ; Finance
Systemic risk and the financial crisis: a primer
How did problems in a relatively small portion of the home mortgage market trigger the most severe financial crisis in the United States since the Great Depression? Several developments played a role, including the proliferation of complex mortgage-backed securities and derivatives with highly opaque structures, high leverage, and inadequate risk management. These, in turn, created systemic risk - that is, the risk that a triggering event, such as the failure of a large financial firm, will seriously impair financial markets and harm the broader economy. This article examines the role of systemic risk in the recent financial crisis. Systemic concerns prompted the Federal Reserve and U.S. Department of the Treasury to act to prevent the bankruptcy of several large financial firms in 2008. The authors explain why the failures of financial firms are more likely to pose systemic risks than the failures of nonfinancial firms and discuss possible remedies for such risks. They conclude that the economy could benefit from reforms that reduce systemic risks, such as the creation of an improved regime for resolving failures of large financial firms.Financial crises ; Systemic risk
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
Dynamic and Energetic Stabilization of Persistent Currents in Bose-Einstein Condensates
We study conditions under which vortices in a highly oblate harmonically
trapped Bose-Einstein condensate (BEC) can be stabilized due to pinning by a
blue-detuned Gaussian laser beam, with particular emphasis on the potentially
destabilizing effects of laser beam positioning within the BEC. Our approach
involves theoretical and numerical exploration of dynamically and energetically
stable pinning of vortices with winding number up to , in correspondence
with experimental observations. Stable pinning is quantified theoretically via
Bogoliubov-de Gennes excitation spectrum computations and confirmed via direct
numerical simulations for a range of conditions similar to those of
experimental observations. The theoretical and numerical results indicate that
the pinned winding number, or equivalently the winding number of the superfluid
current about the laser beam, decays as a laser beam of fixed intensity moves
away from the BEC center. Our theoretical analysis helps explain previous
experimental observations, and helps define limits of stable vortex pinning for
future experiments involving vortex manipulation by laser beams.Comment: 8 pages 5 figure
Observation of vortex dipoles in an oblate Bose-Einstein condensate
We report experimental observations and numerical simulations of the
formation, dynamics, and lifetimes of single and multiply charged quantized
vortex dipoles in highly oblate dilute-gas Bose-Einstein condensates (BECs). We
nucleate pairs of vortices of opposite charge (vortex dipoles) by forcing
superfluid flow around a repulsive gaussian obstacle within the BEC. By
controlling the flow velocity we determine the critical velocity for the
nucleation of a single vortex dipole, with excellent agreement between
experimental and numerical results. We present measurements of vortex dipole
dynamics, finding that the vortex cores of opposite charge can exist for many
seconds and that annihilation is inhibited in our highly oblate trap geometry.
For sufficiently rapid flow velocities we find that clusters of like-charge
vortices aggregate into long-lived dipolar flow structures.Comment: 4 pages, 4 figures, 1 EPAPS fil
Integrating TV/digital data spectrograph system
A 25-mm vidicon camera was previously modified to allow operation in an integration mode for low-light-level astronomical work. The camera was then mated to a low-dispersion spectrograph for obtaining spectral information in the 400 to 750 nm range. A high speed digital video image system was utilized to digitize the analog video signal, place the information directly into computer-type memory, and record data on digital magnetic tape for permanent storage and subsequent analysis
Superorbital expansion tube operation: estimates of flow conditions via numerical simulation
Two new operating conditions of the X3 superorbital expansion tube are studied experimentally and numerically. A two-stage numerical simulation is used to model the flow processes within the whole facility, from the compressed driver gas, through the initial shock-processing of the test gas and then through the unsteady expansion process to the final test flow state. Experimental measurements provide static pressure histories at particular points along the shock and acceleration tubes while the numerical simulations provide complementary information on gas density, temperature and composition. Operating condition properties such as shock speed are both observed in the experiment and produced as a result of the simulation are used to check the reliability of the numerical simulations
Characteristics of Two-Dimensional Quantum Turbulence in a Compressible Superfluid
Under suitable forcing a fluid exhibits turbulence, with characteristics
strongly affected by the fluid's confining geometry. Here we study
two-dimensional quantum turbulence in a highly oblate Bose-Einstein condensate
in an annular trap. As a compressible quantum fluid, this system affords a rich
phenomenology, allowing coupling between vortex and acoustic energy.
Small-scale stirring generates an experimentally observed disordered vortex
distribution that evolves into large-scale flow in the form of a persistent
current. Numerical simulation of the experiment reveals additional
characteristics of two-dimensional quantum turbulence: spontaneous clustering
of same-circulation vortices, and an incompressible energy spectrum with
dependence for low wavenumbers and dependence for high
.Comment: 7 pages, 7 figures. Reference [29] updated for v
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