17,915 research outputs found

    BdbServer++: A User Driven Data Location and Retrieval Tool

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    The adoption of Grid technology has the potential to greatly aid the BaBar experiment. BdbServer was originally designed to extract copies of data from the Objectivity/DB database at SLAC and IN2P3. With data now stored in multiple locations in a variety of data formats, we are enhancing this tool. This will enable users to extract selected deep copies of event collections and ship them to the requested site using the facilities offered by the existing Grid infrastructure. By building on the work done by various groups in BaBar, and the European DataGrid, we have successfully expanded the capabilities of the BdbServer software. This should provide a framework for future work in data distribution.Comment: Paper based on the poster from the 2003 Computing in High Energy and Nuclear Physics (CHEP03), La Jolla, Ca, USA, March 2003, 4 pages, LaTeX, 0 figures. PSN TUCP01

    Real effects of bank capital regulations: global evidence

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    We examine the effect of the full set of bank capital regulations (capital stringency) on loan growth, using bank-level data for a maximum of 125 countries over the period 1998-2011. Contrary to standard theoretical considerations, we find that overall capital stringency only has a weak negative effect on loan growth. In fact, this effect is completely offset if banks hold moderately high levels of capital. Interestingly, the components of capital stringency that have the strongest negative effect on loan growth are those related to the prevention of banks to use as capital borrowed funds and assets other than cash or government securities. In contrast, compliance with Basel guidelines in using Basel- and credit-risk weights has a much less potent effect on loan growth

    Parametric amplification of light in a cavity with a moving dielectric membrane: Landau-Zener problem for the Maxwell field

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    We perform a theoretical investigation into the classical and quantum dynamics of an optical field in a cavity containing a moving membrane ("membrane-in-the-middle" set-up). Our approach is based on the Maxwell wave equation, and complements previous studies based on an effective Hamiltonian. The analysis shows that for slowly moving and weakly reflective membranes the dynamics can be approximated by unitary, first-order-in-time evolution given by an effective Schr\"{o}dinger-like equation with a Hamiltonian that does not depend on the membrane speed. This approximate theory is the one typically adopted in cavity optomechanics and we develop a criterion for its validity. However, in more general situations the full second-order wave equation predicts light dynamics which do not conserve energy, giving rise to parametric amplification (or reduction) that is forbidden under first order dynamics and can be considered to be the classical counterpart of the dynamical Casimir effect. The case of a membrane moving at constant velocity can be mapped onto the Landau-Zener problem but with additional terms responsible for field amplification. Furthermore, the nature of the adiabatic regime is rather different from the ordinary Schr\"odinger case, since mode amplitudes need not be constant even when there are no transitions between them. The Landau-Zener problem for a field is therefore richer than in the standard single-particle case. We use the work-energy theorem applied to the radiation pressure on the membrane as a self-consistency check for our solutions of the wave equation and as a tool to gain an intuitive understanding of energy pumped into/out of the light field by the motion of the membrane.Comment: 27 pages, 15 figure

    Determinants of the loan loss allowance: some cross-country comparisons

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    This paper analyses the determinants of banks’ loan loss allowances for samples of US banks and three non-US samples: a group of 21 countries, Canada and Japan. The model includes fundamental (or non-discretionary) determinants of the allowance such as non-performing loans, and discretionary determinants such as income before the loan loss provision. The results suggest that the loan loss allowance is sensitive to pre-provision income in almost all samples. However, the results also suggest that some variables thought to reflect fundamental factors in US analysis, such as net chargeoffs, are not significant factors for non-US banks.loan loss allowance; accounting standards; international banking; nonperforming loan; discretionary accruals

    Towards the Formal Reliability Analysis of Oil and Gas Pipelines

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    It is customary to assess the reliability of underground oil and gas pipelines in the presence of excessive loading and corrosion effects to ensure a leak-free transport of hazardous materials. The main idea behind this reliability analysis is to model the given pipeline system as a Reliability Block Diagram (RBD) of segments such that the reliability of an individual pipeline segment can be represented by a random variable. Traditionally, computer simulation is used to perform this reliability analysis but it provides approximate results and requires an enormous amount of CPU time for attaining reasonable estimates. Due to its approximate nature, simulation is not very suitable for analyzing safety-critical systems like oil and gas pipelines, where even minor analysis flaws may result in catastrophic consequences. As an accurate alternative, we propose to use a higher-order-logic theorem prover (HOL) for the reliability analysis of pipelines. As a first step towards this idea, this paper provides a higher-order-logic formalization of reliability and the series RBD using the HOL theorem prover. For illustration, we present the formal analysis of a simple pipeline that can be modeled as a series RBD of segments with exponentially distributed failure times.Comment: 15 page
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