213,307 research outputs found

    Implementation of a Quantum Algorithm to Solve Deutsch's Problem on a Nuclear Magnetic Resonance Quantum Computer

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    We demonstrate the use of an NMR quantum computer based on the pyrimidine base cytosine, and the implementation of a quantum algorithm to solve Deutsch's problem.Comment: 16 pages including 6 figures. Minor clarifications as requested by the referee plus updated references. Journal of Chemical Physics, in press (expected publication date August 1st 1998

    Hie-Isolde High Beta Cavity Study and Measurements

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    The upgrade of the ISOLDE machine at CERN foresees a superconducting linac based on two gap independently phased Nb sputtered Quarter Wave Resonators (QWRs) working at 101.28MHz and producing an accelerating field of 6MV/m on axis. A careful study of the fields in the cavity has been carried out in order to pin down the crucial e-m parameters of the structure such as peak fields, quality factor and e-m power dissipated on the cavity wall. A tuning system with about 200kHz frequency range has been developed in order to cope with fabrication tolerances. In this paper we will report on the cavity simulations. The tuning plate design will be described. Finally the frequency measurements on a cavity prototype at room temperature will be presented.Comment: 5 pages, SRF09 Conference in Berli

    Production of Millisecond Dips in Sco X-1 Count Rates by Dead Time Effects

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    Chang et al. (2006) reported millisecond duration dips in the X-ray intensity of Sco X-1 and attributed them to occultations of the source by small trans-Neptunian objects (TNOs). We have found multiple lines of evidence that these dips are not astronomical in origin, but rather the result of high-energy charged particle events in the RXTE PCA detectors. Our analysis of the RXTE data indicates that at most 10% of the observed dips in Sco X-1 could be due to occultations by TNOs, and, furthermore, we find no positive or supporting evidence for any of them being due to TNOs. We therefore believe that it is a mistake to conclude that any TNOs have been detected via occultation of Sco X-1.Comment: Submitted to ApJ; uses emulateapj.cls, 8 pages with 8 figure

    Revising the Solution of the Neutrino Oscillation Parameter Degeneracies at Neutrino Factories

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    In the context of neutrino factories, we review the solution of the degeneracies in the neutrino oscillation parameters. In particular, we have set limits to sin22θ13\sin^2 2\theta_{13} in order to accomplish the unambiguous determination of θ23\theta_{23} and δ\delta. We have performed two different analysis. In the first, at a baseline of 3000 km, we simulate a measurement of the channels νeνμ\nu_e\to\nu_\mu, νeντ\nu_e\to\nu_\tau and νˉμνˉμ\bar{\nu}_\mu\to\bar{\nu}_\mu, combined with their respective conjugate ones, with a muon energy of 50 GeV and a running time of five years. In the second, we merge the simulated data obtained at L=3000 km with the measurement of νeνμ\nu_e\to\nu_\mu channel at 7250 km, the so called 'magic baseline'. In both cases, we have studied the impact of varying the ντ\nu_\tau detector efficiency-mass product, (ϵντ×Mτ)(\epsilon_{\nu_\tau}\times M_\tau), at 3000 km, keeping unchanged the νμ\nu_\mu detector mass and its efficiency. At L=3000 km, we found the existance of degenerate zones, that corresponds to values of θ13\theta_{13}, which are equal or almost equal to the true ones. These zones are extremely difficult to discard, even when we increase the number of events. However, in the second scenario, this difficulty is overcomed, demostrating the relevance of the 'magic baseline'. From this scenario, the best limits of sin22θ13\sin^2 2\theta_{13}, reached at 3σ3\sigma, for sin22θ23=0.95\sin^2 2\theta_{23}=0.95, 0.975 and 0.99 are: 0.008, 0.015 and 0.045, respectively, obtained at δ=0\delta=0, and considering (ϵντ×Mτ)125(\epsilon_{\nu_\tau}\times M_\tau) \approx 125, which is five times the initial efficiency-mass combination.Comment: 40 pages, 18 figures; added references, corrected typos, updated Eq (15c

    Investigating presentational change in UK annual reports: a longitudinal perspective

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    This article examines structural and format changes in annual reports of U.K. listed companies from 1965 to 2004 with a particular focus on graph use. The article compares a new sample of 2004 annual reports with preexisting samples by Lee and by Beattie and Jones. Lee's identified trends continue. There has been a sharp increase in page length, voluntary information, and narrative information, particularly among large listed companies. A detailed analysis of voluntary disclosure indicates changes in the incidence and pattern of generic sections. Graph usage is now universal. However, key financial graph use has slightly declined, replaced by graphs depicting other operating issues. Impression management through selectivity, graphical measurement distortion, and manipulation of the length of time series graphed are common. Overall, annual reports continue to exhibit many features of public relations documents rather than financially driven, statutory documents, and the analysis of graph usage suggests a need for policy guidelines to protect users

    Usability of digital libraries

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