27,617 research outputs found

    The 10-ft. space simulator at the Jet Propulsion Laboratory

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    Pumping, vacuum, cryogenic, solar simulation, and supporting systems for space simulator facilit

    Comparison of LOQC C-sign gates with ancilla inefficiency and an improvement to functionality under these conditions

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    We compare three proposals for non-deterministic C-sign gates implemented using linear optics and conditional measurements with non-ideal ancilla mode production and detection. The simplified KLM gate [Ralph et al, Phys.Rev.A {\bf 65}, 012314 (2001)] appears to be the most resilient under these conditions. We also find that the operation of this gate can be improved by adjusting the beamsplitter ratios to compensate to some extent for the effects of the imperfect ancilla.Comment: to appear in PR

    Magnetic activity, differential rotation and dynamo action in the pulsating F9IV star KIC 5955122

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    We present photometric spot modeling of the nearly four-year long light-curve of the Kepler target KIC 5955122 in terms of persisting dark circular surface features. With a Bayesian technique, we produced a plausible surface map that shows dozens of small spots. After some artifacts are removed, the residuals are at ±0.16\pm 0.16\,mmag. The shortest rotational period found is P=16.4±0.2P = 16.4 \pm 0.2 days. The equator-to-pole extrapolated differential rotation is 0.25±0.020.25 \pm 0.02 rad/d. The spots are roughly half as bright as the unperturbed stellar photosphere. Spot latitudes are restricted to the zone ±60\pm 60^\circ latitude. There is no indication for any near-pole spots. In addition, the p-mode pulsations enabled us to determine the evolutionary status of the star, the extension of the convective zone, and its radius and mass. We discuss the possibility that the clear signature of active regions in the light curve of the F9IV star KIC 5955122 is produced by a flux-transport dynamo action at the base of the convection zone. In particular, we argue that this star has evolved from an active to a quiet status during the Q0--Q16 period of observation, and we predict, according to our dynamo model, that the characteristic activity cycle is of the order of the solar one.Comment: 9 pages, 12 figures, to be published on A&

    Weak products of complete Pick spaces

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    Let H\mathcal H be the Drury-Arveson or Dirichlet space of the unit ball of Cd\mathbb C^d. The weak product HH\mathcal H\odot\mathcal H of H\mathcal H is the collection of all functions hh that can be written as h=n=1fngnh=\sum_{n=1}^\infty f_n g_n, where n=1fngn<\sum_{n=1}^\infty \|f_n\|\|g_n\|<\infty. We show that HH\mathcal H\odot\mathcal H is contained in the Smirnov class of H\mathcal H, i.e. every function in HH\mathcal H\odot\mathcal H is a quotient of two multipliers of H\mathcal H, where the function in the denominator can be chosen to be cyclic in H\mathcal H. As a consequence we show that the map NclosHHN\mathcal N \to clos_{\mathcal H\odot\mathcal H} \mathcal N establishes a 1-1 and onto correspondence between the multiplier invariant subspaces of H\mathcal H and of HH\mathcal H\odot\mathcal H. The results hold for many weighted Besov spaces H\mathcal H in the unit ball of Cd\mathbb C^d provided the reproducing kernel has the complete Pick property. One of our main technical lemmas states that for weighted Besov spaces H\mathcal H that satisfy what we call the multiplier inclusion condition any bounded column multiplication operator Hn=1H\mathcal H \to \oplus_{n=1}^\infty \mathcal H induces a bounded row multiplication operator n=1HH\oplus_{n=1}^\infty \mathcal H \to \mathcal H. For the Drury-Arveson space Hd2H^2_d this leads to an alternate proof of the characterization of interpolating sequences in terms of weak separation and Carleson measure conditions.Comment: minor change

    Reference System Description

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    Several candidate antenna configurations are evaluated in terms of weight, efficiency, and structural rigidity. Particular emphasis is given to the waveguide slot array and its application to solar power satellites SPS. The electronic aspects of an SPS specific waveguide slot array are defined

    X-RAY OBSERVATIONS OF SN 1006 WITH INTEGRAL

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    We have used 1000 ksec of on-source, and 500 ksec of 10 degrees off-source INTEGRAL data of SN 1006 to characterize the synchrotron emission, and attempt to detect non-thermal bremsstrahlung, using the combination of IBIS and JEM-X spatial and spectral coverage. With the earlier 750 ksec on source data, we have detected the limbs of SN 1006 with JEM-X between 2.4 and 8.4 keV bands. The source was not detected with either ISGRI orSPI above 20 keV. The ISGRI upper limit is about a factor of four above current model predictions, but conrms the presence of steepening in the power-law extrapolated from lower energies (< 4 keV)

    Did the ban on smoking reduce the revenue in pubs and restaurants in Norway?

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    After 16 years of exemptions from the ban on indoor smoking in other places of work, Norway became the second country after Ireland to implement a smoke-free regime in pubs and restaurants. This paper evaluates the economic impact on the hospitality sector in a northern region with a cold climate. The data consists of bi-monthly observations of revenues in restaurants and pubs starting in January 1999 and ending in August 2007. Auto-regressive integrated moving average (ARIMA) intervention analysis was used to test for possible economic impacts, controlling for variations in temperature. The ban on smoking did not have a statistically significant effect on revenue in restaurants or on restaurant revenue as a share of personal consumption. There is also no evidence that the ban reduce revenues in bars, but there is some indication that it may have reduced bar revenue as a share of personal consumption. Conclusion: A large body of research has found no negative economic effect of smoke-free legislation on restaurant and bar sales in the United States, Australia and elsewhere Our study confirms these results in a northern region with a cold climate with respect to restaurants, but the results was more mixed for bars.Tobacco; economics; business; passive smoking; legislation

    The LOFT (Large Observatory for X-ray Timing) background simulations

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    The Large Observatory For X-ray Timing (LOFT) is an innovative medium-class mission selected for an assessment phase in the framework of the ESA M3 Cosmic Vision call. LOFT is intended to answer fundamental questions about the behaviour of matter in the very strong gravitational and magnetic fields around compact objects. With an effective area of ~10 m^2 LOFT will be able to measure very fast variability in the X-ray fluxes and spectra. A good knowledge of the in-orbit background environment is essential to assess the scientific performance of the mission and to optimize the instrument design. The two main contributions to the background are cosmic diffuse X-rays and high energy cosmic rays; also, albedo emission from the Earth is significant. These contributions to the background for both the Large Area Detector and the Wide Field Monitor are discussed, on the basis of extensive Geant-4 simulations of a simplified instrumental mass model.Comment: Proceedings of SPIE, Vol. 8443, Paper No. 8443-209, 201

    Scattering of first and second sound waves by quantum vorticity in superfluid Helium

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    We study the scattering of first and second sound waves by quantum vorticity in superfluid Helium using two-fluid hydrodynamics. The vorticity of the superfluid component and the sound interact because of the nonlinear character of these equations. Explicit expressions for the scattered pressure and temperature are worked out in a first Born approximation, and care is exercised in delimiting the range of validity of the assumptions needed for this approximation to hold. An incident second sound wave will partly convert into first sound, and an incident first sound wave will partly convert into second sound. General considerations show that most incident first sound converts into second sound, but not the other way around. These considerations are validated using a vortex dipole as an explicitely worked out example.Comment: 24 pages, Latex, to appear in Journal of Low Temperature Physic

    Quantum-dot thermometry

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    We present a method for the measurement of a temperature differential across a single quantum dot that has transmission resonances that are separated in energy by much more than the thermal energy. We determine numerically that the method is accurate to within a few percent across a wide range of parameters. The proposed method measures the temperature of the electrons that enter the quantum dot and will be useful in experiments that aim to test theory which predicts quantum dots are highly-efficient thermoelectrics.Comment: 3 pages, 4 Figure
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