Superfluid toroidal currents in atomic condensates

The dynamics of toroidal condensates in the presence of condensate flow and dipole perturbation have been investigated. The Bogoliubov spectrum of condensate is calculated for an oblate torus using a discrete-variable representation and a spectral method to high accuracy. The transition from spheroidal to toroidal geometry of the trap displaces the energy levels into narrow bands. The lowest-order acoustic modes are quantized with the dispersion relation $\omega \sim |m| \omega_s$ with $m=0,\pm 1,\pm 2, ...$. A condensate with toroidal current $\kappa$ splits the $|m|$ co-rotating and counter-rotating pair by the amount: $\Delta E \approx 2 |m|\hbar^2 \kappa < r^{-2}>$. Radial dipole excitations are the lowest energy dissipation modes. For highly occupied condensates the nonlinearity creates an asymmetric mix of dipole circulation and nonlinear shifts in the spectrum of excitations so that the center of mass circulates around the axis of symmetry of the trap. We outline an experimental method to study these excitations.Comment: 8 pages, 8 figure

Adapting National Mapping &amp; Cadastral Agencies business models to open data supply: the survey results

Since 2009, Open Government Data initiatives have been launched worldwide and the concept of open data is gaining momentum. Open data are often associated with realizing ambitions, such as a more transparent and efficient government, solving societal problems and increased economic value. There has been ample literature describing the (potential) benefits of open data. However, to switch to an open data policy may pose a challenge to the business model of National Mapping &amp; Cadastral Agencies (NMCAs), especially if they are required to generate sufficient revenue to cover a substantial part of their operating costs. This research aims to assess the effects of open data policies on the business models of NMCAs and which adaptations have been made to cope with revenue losses due to open data supply. In March and April 2017, we surveyed European NMCAs to find out which strategies NMCAs employ to be able to (re)finance operational costs and to ensure long-term sustainability of (open) data. This report provides the initial outcomes of the survey and will provide an input for a workshop on Sustainable Open Data Business Models for NMCAs, to be held 18-19 September 2017 in Delft, The Netherlands. This workshop will bring together the NMCAs to present and share their experiences of open data and discuss the research results with representatives of academia.All rights of translation and reproduction are reserved on behalf of EuroSDR.OLD Geo-information and Land Developmen