3,468 research outputs found

    New Constraints on the Yukawa-Type Hypothetical Interaction From The Recent Casimir Force Measurement

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    We calculate the constraints on the constants of hypothetical long-range interactions which follow from the recent measurement of the Casimir force. A comparison with previous constraints is given. The new constraints are up to a factor of 3000 stronger in some parameter regions .Comment: 10 pages, Latex, 2 figures, to appear in Phys. Rev.

    Universality in the Gravitational Stretching of Clocks, Waves and Quantum States

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    There are discernible and fundamental differences between clocks, waves and physical states in classical physics. These fundamental concepts find a common expression in the context of quantum physics in gravitational fields; matter and light waves, quantum states and oscillator clocks become quantum synonymous through the Planck-Einstein-de Broglie relations and the equivalence principle. With this insight, gravitational effects on quantum systems can be simply and accurately analyzed. Apart from providing a transparent framework for conceptual and quantitative thinking on matter waves and quantum states in a gravitational field, we address and resolve with clarity the recent controversial discussions on the important issue of the relation and the crucial difference between gravimetery using atom interferometers and the measurement of gravitational time dilation.Comment: Gravity Research Foundation honorable mention, 201

    MIG gas shielding : Economic savings without detriment to quality

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    Over the years a number of claims have been made related to potential savings of the shielding gas used in the MIG process. A number of work streams have been set up to consider such areas from a technical and economic standpoint. The use of small helium additions has particular benefits and despite an increase in unit cost, the overriding benefits are achieved in reduced manhour cost. A similar situation has been established when using a high frequency process to switch shielding gases during welding. The outcome from this was very similar to that already described. Overlaid on these has been the increasing use of a technique that visualises actual gas flow during welding by the use of laser backlighting. Some preliminary work in this area is described particularly related to the effect of drafts on the gas distribution. A recent development on the market place is a piece of equipment, which regulates the gas flow automatically and synchronously with the welding current. Gas savings in the region of 50-60% have been obtained. Data has been produced to illustrate these benefits. The potential benefit of developing a computational fluid dynamic model of the gas flow is also described, and early development stages of the model shown. However, there will always exist the very basic management need to minimise leaks from the gas delivery systems

    Dual-doped thermographic phosphor particles as surrogates for green fluorescent protein-labeled cells in tests of cytometric neurocatheters

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    We investigated the laser-induced fluorescence of particles of a compound thermographic phosphorLa2O2S:Eu(1%) and Gd2O2S:Eu(1%) to see if they can serve as a surrogate for cells transfected with the green fluorescent protein, in tests of neurocatheters used for intraparenchymal celldelivery. At an excitation wavelength of 337 nm and a concentration of ≈2×106 particles ml−1, the resulting slurries produced fluorescence intensities at 625 nm that were within a factor of 2 of those produced by similar number densities of relevant cells, thus suggesting the utility of this approach
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