37,929 research outputs found

    New insights from inside-out Doppler tomography

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    We present preliminary results from our investigation into using an 'inside-out' velocity space for creating a Doppler tomogram. The aim is to transpose the inverted appearance of the Cartesian velocity space used in normal Doppler tomography. In a comparison between normal and inside-out Doppler tomograms of cataclysmic variables, we show that the inside-out velocity space has the potential to produce new insights into the accretion dynamics in these systems.Comment: 4 pages, 4 figures, conference: The Golden Age of Cataclysmic Variables and Related Objects II, Palermo 201

    The Effective Δmee2\Delta m^2_{ee} in Matter

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    In this paper we generalize the concept of an effective Δmee2\Delta m^2_{ee} for νe/νˉe\nu_e/\bar{\nu}_e disappearance experiments, which has been extensively used by the short baseline reactor experiments, to include the effects of propagation through matter for longer baseline νe/νˉe\nu_e/\bar{\nu}_e disappearance experiments. This generalization is a trivial, linear combination of the neutrino mass squared eigenvalues in matter and thus is not a simple extension of the usually vacuum expression, although, as it must, it reduces to the correct expression in the vacuum limit. We also demonstrated that the effective Δmee2\Delta m^2_{ee} in matter is very useful conceptually and numerically for understanding the form of the neutrino mass squared eigenstates in matter and hence for calculating the matter oscillation probabilities. Finally we analytically estimate the precision of this two-flavor approach and numerically verify that it is precise at the sub-percent level.Comment: 9 pages, 6 figures, 1 table, comments welcom

    GENIE observations of small scale astrophysical processes in star forming regions and quasars

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    The VLTI/GENIE configuration will operate using at least 4 of the VLTI telescopes (and possibly with one or more of the AT telescopes in the future if adaptive optics become available on them). GENIE effectively can be thought of as a 'smart' coronagraph, enabling high dynamic range imaging to be achieved at moderate spatial resolution, with high rejection of the emission of a central bright point source. However, but this bright source rejection may only provide a rather moderate image quality (due to the few baselines and transfer function on the sky). Operated in this way, only limited image reconstruction is possible since classical radio and millimeter wavelength interferometry techniques are not directly applicable to the outputs of optical interferometers because the absolute phases are generally not measured. However, measurements of visibility and closure phase could lead to situations where image reconstruction becomes possible. This paper addresses the issue of whether there are areas outside of the exoplanet search where it might be able to make a useful impact on astronomy.Comment: Proceedings of the Genie-Darwin Workshop - Hunting for Planet

    An Analysis of the Stabilizing and Welfare Effects of Intervention in Spot and Futures Markets

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    This paper analyzes the effects of three alternative rules on the long-run distributions of both the spot and futures prices ina single commodity market, in which the key behavioral relationships are derived from the optimizing behavior of producers and speculators.The rules considered include: (i) leaning against the wind in the spot market; (ii) utility maximizing speculative behavior by the stabilization authority in the futures market; (iii) leaning against the wind in the futures market. Since the underlying model is sufficiently complex to preclude analytical solutions, the analysis makes extensive use of simulation methods. As a general proposition we find that intervention in the futures market is not as effective in stabilizing either the spot price of the futures price as is intervention in the spot market. Indeed, Rule (iii), while stabilizing the futures price may actually destabilize the spot price. Furthermore, the analogous type of rule undertaken in the spot market will always stabilize the futures price to a greater degree than it does the spot price. The welfare implications of these rules are also discussed. Our analysis shows how these can generate rather different distributions of welfare gains, including the overall benefits.

    Debt Financing and Financial Flexibility Evidence from Pro-active Leverage Increases

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    Firms that intentionally increase leverage through substantial debt issuances do so primarily as a response to operating needs rather than a desire to make a large equity payout. Subsequent debt reductions are neither rapid, nor the result of pro-active attempts to rebalance the firm’s capital structure towards a long-run target. Instead, the evolution of the firm’s leverage ratio depends primarily on whether or not the firm produces a financial surplus. In fact, firms that generate subsequent deficits tend to cover these deficits predominantly with more debt even though they exhibit leverage ratios that are well above estimated target levels. While many of our findings are difficult to reconcile with traditional capital structure models, they are broadly consistent with a capital structure theory in which financial flexibility, in the form of unused debt capacity, plays an important role in capital structure choices.
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