Information Retrieval across Information Visualization

This article presents the analytical and retrieval potential of visualization maps. Obtained maps were tested as information retrieval (IR) interface. The collection of documents derived from the ACM Digital Library was mapped on the sphere surface. Proposed approach uses nonlinear similarity of documents by comparing ascribed thematic categories and thereby development of semantic connections between them. For domain analysis the newest IT trend - Cloud Computing was monitored across time period 2007-2009. Visualization reflects evolution, dynamics and relational fields of cloud technology as well as its paradigmatic property

Soliton trains and vortex streets as a form of Cerenkov radiation in trapped Bose-Einstein condensates

We numerically study the nucleation of gray solitons and vortex-antivortex pairs created by a moving impurity in, respectively, 1D and 2D Bose-Einstein condensates (BECs) confined by a parabolic potential. The simulations emulate the motion of a localized laser-beam spot through the trapped condensate. Our results for the 1D case indicate that, due to the inhomogeneity of the BEC density, the critical speed for nucleation, as a function of the condensate density displays two distinct dependences. In particular, the square root of the critical density for nucleation as a function of speed displays two different linear regimes corresponding to small and large velocities. Effectively, the emission of gray solitons and vortex-antivortex pairs occurs for any velocity of the impurity, as any given velocity will be supercritical in a region with a sufficiently small density. At longer times, the first nucleation is followed by generation of an array of solitons in 1D ("soliton train") or vortex pairs in 2D ("vortex street") by the moving object. © 2006 IMACS

Transport properties of a Bose-Einstein condensate with tunable interactions in the presence of a disordered or single defect potential

Bose-Einstein condensates (BECs) have proven to be remarkable systems with which to study some of the foundational models of condensed matter physics. The observation of a critical velocity for the breakdown of superfluidity in a BEC and the superfluid to Mott insulator transition observed in a BEC trapped by an optical lattice are but two examples of the, by now, dozens of exciting results in this field, which combines theoretical tools from condensed matter physics with state-of-the-art experimental techniques from ultra-cold atomic physics. However, any real condensed matter system has to contend with the effects of disorder, a phenomena notably absent in the inherently clean BEC systems. We have developed and implemented a way to add well characterized disorder in a controlled way to the otherwise clean BEC system using the light field from a laser speckle pattern. Using this system, we have investigated the effects of disorder or a single Gaussian defect, on the collective dipole motion of a BEC of 7Li in an optical trap. In addition, we perform transport experiments on a weakly interacting BEC expanding in a disordered one-dimensional atom wave-guide. We have observed that in such a system, the wave nature of matter can lead to spectacular and counterintuitive phenomena. Specifically, we verify that this system exhibits Anderson localization, a phenomena fundamentally resulting from the interference of multiply scattered matter waves. In such a state, the localized gas behaves as an insulator in a regime where it is classically expected to be conducting. We also present results of experiments regarding a repulsive BEC scattering from a semi-permeable, single defect potential. We investigate the transport properties of such a system with special emphasis on the velocity and defect strength dependent dissipation of the collective dipole motion of the BEC. Finally, we present the results of our experiments on the scattering properties of bright matter wave solitons. We have observed fragmentation of the soliton in a disordered potential as well as both splitting and recombination of a soliton after interacting with a single repulsive defect potential