9,551 research outputs found

    Supervision of large complex banking organizations

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    The long-term trends of consolidation and innovation in the U.S. banking system have intensified over the past decade. A small number of banking organizations now hold a larger portion of the banking system's assets, and, at the same time, their activities have become more complex. As a result, the Federal Reserve has altered its approach to the supervision of the largest, most complex banking organizations (LCBOs). This new approach focuses on the most important risks facing U.S. banking organizations and the ways in which these risks are managed. This article discusses the Federal Reserve's risk-focused supervision program as applied to LCBOs.Bank supervision ; Bank holding companies

    A Fast Chi-squared Technique For Period Search of Irregularly Sampled Data

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    A new, computationally- and statistically-efficient algorithm, the Fast Ļ‡2\chi^2 algorithm, can find a periodic signal with harmonic content in irregularly-sampled data with non-uniform errors. The algorithm calculates the minimized Ļ‡2\chi^2 as a function of frequency at the desired number of harmonics, using Fast Fourier Transforms to provide O(Nlogā”N)O (N \log N) performance. The code for a reference implementation is provided.Comment: Source code for the reference implementation is available at http://public.lanl.gov/palmer/fastchi.html . Accepted by ApJ. 24 pages, 4 figure

    Afterglows of Gamma-Ray Bursts: Short vs. Long GRBs

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    We compiled a large sample of Swift-era photometric data on long (Type II) and short (Type I) GRB afterglows. We compare the luminosity and energetics of the different samples to each other and to the afterglows of the pre-Swift era. Here, we present the first results of these studies.Comment: Conference Proceedings, "Gamma-Ray Bursts 2007", Santa Fe, shortened poster presentation; 4 pages, 3 figures; for full updated papers, go here to arXiv:0712.2186 and also here to arXiv:0804.195

    Strong spectral evolution during the prompt emission of GRB 070616

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    Swift has revealed features in GRB early light curves, such as steep decays and X-ray flares, whose properties are consistent with an internal origin though they are far from understood. The steep X-ray decay is often explained using the curvature effect; however a significant number of GRBs display strong spectral evolution during this phase, and a new mechanism must be invoked to explain this. Of particular interest are the longest duration GRBs in which the early emission can be studied in most detail. Here we present data for GRB 070616, in which the prompt emission shows a complex multipeaked structure, leading to one of the longest prompt emission durations ever recorded. We take advantage of extensive coverage of such a long burst by all Swift instruments. Combining data from Swift and Suzaku we study the evolution of the prompt emission spectrum, following the temporal variability of the peak energy and spectral slope.Comment: 4 pages, 2 figures (Fig 1 in colour), contributed talk, submitted to the proceedings of Gamma Ray Bursts 2007, Santa Fe, New Mexico, November 5-9 200

    The ECLAIRs telescope onboard the SVOM mission for gamma-ray burst studies

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    The X- and gamma-ray telescope ECLAIRs onboard the future mission for gamma-ray burst studies SVOM (Space-based multi-band astronomical Variable Objects Monitor) is foreseen to operate in orbit from 2013 on. ECLAIRs will provide fast and accurate GRB triggers to other onboard telescopes, as well as to the whole GRB community, in particular ground-based follow-up telescopes. With its very low energy threshold ECLAIRs is particularly well suited for the detection of highly redshifted GRB. The ECLAIRs X- and gamma-ray imaging camera (CXG), used for GRB detection and localization, is combined with a soft X-ray telescope (SXT) for afterglow observations and position refinement. The CXG is a 2D-coded mask imager with a 1024 cm2^2 detection plane made of 80Ɨ\times80 CdTe pixels, sensitive from 4 to 300 keV, with imaging capabilities up to about 120 keV and a localization accuracy better than 10 arcmin. The CXG permanently observes a 2 sr-wide field of the sky and provides photon data to the onboard science and triggering unit (UTS) which detects GRB by count-rate increases or by the appearance of a new source in cyclic sky images. The SXT is a mirror focusing X-ray telescope operating from 0.3 to 2 keV with a sensitivity of 1 mCrab for 100 s observations. The spacecraft slews within ā‰ƒ\simeq3 min in order to place the GRB candidate into the 23Ɨ\times23 arcmin2^2 field of view of the SXT, after which it refines the GRB position to about 10 arcsec. GRB alerts are transmitted to ground-observers within tens of seconds via a VHF network and all detected photons are available hours later for detailed analysis. In this paper we present the ECLAIRs concepts, with emphasis on the expected performances.Comment: on behalf of the ECLAIRs collaboration. Proceedings of Gamma-Ray Bursts 2007 conference, Santa Fe, USA, 5-9 November 2007. Published in AIP conf. proc. 1000, 581-584 (2008
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