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We study theoretically the macroscopic interference of two independent Bose condensates released from a double potential trap. The observation of fringes could serve as a test for the paradigm of broken gauge symmetry. By numerical solution of the nonlinear Schrödinger equation in three dimensions, the consecutive stages of expansion, overlap, and interference are investigated in order to facilitate the design of future experiments. The phase-space dynamics of the condensates is analyzed by means of the Wigner function. It turns out that the distance of interference fringes grows linearly in time with a velocity inversely proportional to the initial distance of the two condensates. The collisional reduction of the fringe visibility is estimated.

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Clearly, despite effective abatement measures, atmospheric Pb will continue to be dominated by anthropogenic mobilization. The influence from long-range transport can be expected to decrease with the effectiveness of abatement programmes in neighbouring countries of the region.

Abstract. The change of the chemical composition of the near-ground level atmospheric aerosol was studied during two summer episodes by a Lagrangian type of experimental approach. Bulk and single-particle chemical analyses of ions and elements in the particulate phase were deployed. N(-III) and N(V) components were also measured in the gas-phase. The measurements were completed by particle size distributions.Secondary inorganic aerosols (SIA) and fine particles of ≈0.2-0.4 µm size were still elevated 50 km downwind of the city. The direct comparison of transport over the city in contrast to transport over the surrounding areas showed that SIA was formed from emission from the city within less than 3 h. Relative increases, i.e., enrichment during transport were observed for primary and secondary aerosol components. The degree of mixing on the individual particle level increased significantly during transport in the area. In particular, newly emitted carbonaceous particles became internally mixed within hours with pre-existing sulphate particles. Mostly due to secondary aerosol formation the average particle size (mass median diameter) of major constituents of the aerosol was significantly decreased while being transported over 13 h. Given recent insights which link fine particles number and mass concentrations with health risks, the results suggest that rural populations in areas which frequently are located within an urban plume might run an elevated health risk relative to populations in areas not affected by urban plumes.

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