24,131 research outputs found

    Correlations in a BEC collision: First-principles quantum dynamics with 150 000 atoms

    Full text link
    The quantum dynamics of colliding Bose-Einstein condensates with 150 000 atoms are simulated directly from the Hamiltonian using the stochastic positive-P method. Two-body correlations between the scattered atoms and their velocity distribution are found for experimentally accessible parameters. Hanbury Brown-Twiss or thermal-like correlations are seen for copropagating atoms, while number correlations for counterpropagating atoms are even stronger than thermal correlations at short times. The coherent phase grains grow in size as the collision progresses with the onset of growth coinciding with the beginning of stimulated scattering. The method is versatile and usable for a range of cold atom systems.Comment: 4 pages, 4 figures. v2: Rewording and style changes, minor except for rewrite of background on the positive-P representation. Original research unchange

    Severability of Covenants in Partial Restraint of Trade: A New Rule

    Get PDF

    GPS and property surveying

    Get PDF
    In 2010 the Global Positioning System (GPS) developed by the United States military was the best known Global Navigation Satellite System (GNSS). Others included Russia’s GLONASS, China’s COMPASS and Europe’s GALILEO systems. Although military satellite navigation systems can be traced back to the 1960s, their civilian uses emerged in the 1980s, initially limited to navigation positioning, not property surveying. Property surveying methods have varied both between and within nations. However, GPS surveying with some supporting legislation, had, by the early years of the 21st century, sufficiently developed to meet the needs of the property sector. This chapter looks at this development, and its implications with respect to cadastral surveying

    Relevance of Catholic Medical Schools in Modern Society

    Get PDF

    An Exploration into the Ethics of Cloning Endangered Species

    Full text link
    Researchers are cloning endangered species, expanding the debate on human cloning to include both the value of evolution and the question of whether ethical issues affecting endangered species should be defined in terms of human medical benefit. In this paper, the author explores these questions and others with evolutionary biologist Kathryn Rodriguez-Clark, philosopher Holmes Rolston, III, and toxicologist Don Sparling. Whether or not we are ready to formulate ethics on the subject, if we do not enter into a serious dialogue now, then we allow the question of whether to clone any species—including our own— to be decided for us

    The Grassmannian Origin Of Dual Superconformal Invariance

    Full text link
    A dual formulation of the S Matrix for N=4 SYM has recently been presented, where all leading singularities of n-particle N^{k-2}MHV amplitudes are given as an integral over the Grassmannian G(k,n), with cyclic symmetry, parity and superconformal invariance manifest. In this short note we show that the dual superconformal invariance of this object is also manifest. The geometry naturally suggests a partial integration and simple change of variable to an integral over G(k-2,n). This change of variable precisely corresponds to the mapping between usual momentum variables and the "momentum twistors" introduced by Hodges, and yields an elementary derivation of the momentum-twistor space formula very recently presented by Mason and Skinner, which is manifestly dual superconformal invariant. Thus the G(k,n) Grassmannian formulation allows a direct understanding of all the important symmetries of N=4 SYM scattering amplitudes.Comment: 9 page
    • …
    corecore