Dynamical excitations in the collision of 2D Bose-Einstein condensates

We carry out simulations of the collision of two components of an adiabatically divided, quasi-2D BEC. We identify under, over and critically damped regimes in the dipole oscillations of the components according to the balance of internal and centre-of-mass (c.m.) energies of the components and investigate the creation of internal excitations. We distinguish the behaviour of this system from previous studies of quasi-1D BEC's. In particular we note that the nature of the internal excitations is only essentially sensitive to an initial phase difference between the components in the overdamped regime.Comment: 17 pages, 9 figure

Time evolution in the Morse potential using supersymmetry: dissociation of the NO molecule

We present an algebraic method for treating molecular vibrations in the Morse potential perturbed by an external laser field. By the help of a complete and normalizable basis we transform the Schr\"{o}dinger equation into a system of coupled ordinary differential equations. We apply our method to calculate the dissociation probability of the NO molecule excited by chirped laser pulses. The dependence of the molecular dipole-moment on the interatomic separation is determined by a quantum-chemical method, and the corresponding transition dipole moments are given by approximate analytic expressions. These turn out to be very small between neighboring stationary states around the vibrational quantum number $m=42$, therefore we propose to use additional pulses in order to skip this trapping state, and to obtain a reasonable dissociation probability.Comment: 4 pages, 3 figure

Magnetoroton scattering by phonons in the fractional quantum Hall regime

Motivated by recent phonon spectroscopy experiments in the fractional quantum Hall regime we consider processes in which thermally excited magnetoroton excitations are scattered by low energy phonons. We show that such scattering processes can never give rise to dissociation of magnetorotons into unbound charged quasiparticles as had been proposed previously. In addition we show that scattering of magnetorotons to longer wavelengths by phonon absorption is possible because of the shape of the magnetoroton dispersion curve and it is shown that there is a characteristic cross-over temperature above which the rate of energy transfer to the electron gas changes from an exponential (activated) to a power law dependence on the effective phonon temperature.Comment: LaTex document, 3 eps figures. submitted to Phys Rev

Series solutions for a static scalar potential in a Salam-Sezgin Supergravitational hybrid braneworld

The static potential for a massless scalar field shares the essential features of the scalar gravitational mode in a tensorial perturbation analysis about the background solution. Using the fluxbrane construction of [8] we calculate the lowest order of the static potential of a massless scalar field on a thin brane using series solutions to the scalar field's Klein Gordon equation and we find that it has the same form as Newton's Law of Gravity. We claim our method will in general provide a quick and useful check that one may use to see if their model will recover Newton's Law to lowest order on the brane.Comment: 5 pages, no figure

A linear domain decomposition method for two-phase flow in porous media

This article is a follow up of our submitted paper [11] in which a decomposition of the Richards equation along two soil layers was discussed. A decomposed problem was formulated and a decoupling and linearisation technique was presented to solve the problem in each time step in a fixed point type iteration. This article extends these ideas to the case of two-phase in porous media and the convergence of the proposed domain decomposition method is rigorously shown.Comment: 8 page

The Impact of Business-Cycle Fluctuations on Private-Label Share

This study investigates the cyclical dependence of private-label success in four countries. The results show that private-label share behaves countercyclically. Moreover, asymmetries are present in both the extent and speed of up- and down-ward movements in private-label share over the business cycle. Finally, part of private-labels’ share gain during contractions is found to be permanent

Modeling Multi-Wavelength Stellar Astrometry. I. SIM Lite Observations of Interacting Binaries

Interacting binaries consist of a secondary star which fills or is very close to filling its Roche lobe, resulting in accretion onto the primary star, which is often, but not always, a compact object. In many cases, the primary star, secondary star, and the accretion disk can all be significant sources of luminosity. SIM Lite will only measure the photocenter of an astrometric target, and thus determining the true astrometric orbits of such systems will be difficult. We have modified the Eclipsing Light Curve code (Orosz & Hauschildt 2000) to allow us to model the flux-weighted reflex motions of interacting binaries, in a code we call REFLUX. This code gives us sufficient flexibility to investigate nearly every configuration of interacting binary. We find that SIM Lite will be able to determine astrometric orbits for all sufficiently bright interacting binaries where the primary or secondary star dominates the luminosity. For systems where there are multiple components that comprise the spectrum in the optical bandpass accessible to SIM Lite, we find it is possible to obtain absolute masses for both components, although multi-wavelength photometry will be required to disentangle the multiple components. In all cases, SIM Lite will at least yield accurate inclinations, and provide valuable information that will allow us to begin to understand the complex evolution of mass-transferring binaries. It is critical that SIM Lite maintains a multi-wavelength capability to allow for the proper deconvolution of the astrometric orbits in multi-component systems.Comment: 12 pages, 6 figures, 6 tables. Accepted for publication in the Astrophysical Journa

The ACIGA Data Analysis programme

The Data Analysis programme of the Australian Consortium for Interferometric Gravitational Astronomy (ACIGA) was set up in 1998 by the first author to complement the then existing ACIGA programmes working on suspension systems, lasers and optics, and detector configurations. The ACIGA Data Analysis programme continues to contribute significantly in the field; we present an overview of our activities.Comment: 10 pages, 0 figures, accepted, Classical and Quantum Gravity, (Proceedings of the 5th Edoardo Amaldi Conference on Gravitational Waves, Tirrenia, Pisa, Italy, 6-11 July 2003

HST Fine Guidance Sensor Astrometric Parallaxes for Three Dwarf Novae: SS Aurigae, SS Cygni, and U Geminorum

We report astrometric parallaxes for three well known dwarf novae obtained using the Fine Guidance Sensors on the Hubble Space Telescope. We found a parallax for SS Aurigae of Pi = 5.00 +/- 0.64 mas, for SS Cygni we found Pi = 6.02 +/- 0.46 mas, and for U Geminorum we obtained Pi = 10.37 +/- 0.50 mas. These represent the first true trigonometric parallaxes of any dwarf novae. We briefly compare these results with previous distance estimates. This program demonstrates that with a very modest amount of HST observing time, the Fine Guidance Sensors can deliver parallaxes of unrivaled precision.Comment: 15 pages, 2 Table