27,617 research outputs found
The 10-ft. space simulator at the Jet Propulsion Laboratory
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
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
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 \,mmag. The shortest rotational period found is days. The equator-to-pole extrapolated differential rotation is rad/d. The spots are roughly half as bright as the unperturbed stellar
photosphere. Spot latitudes are restricted to the zone 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
Let be the Drury-Arveson or Dirichlet space of the unit ball of
. The weak product of is
the collection of all functions that can be written as , where . We show that
is contained in the Smirnov class of ,
i.e. every function in is a quotient of two
multipliers of , where the function in the denominator can be
chosen to be cyclic in . As a consequence we show that the map
establishes a 1-1
and onto correspondence between the multiplier invariant subspaces of and of .
The results hold for many weighted Besov spaces in the unit ball
of provided the reproducing kernel has the complete Pick
property. One of our main technical lemmas states that for weighted Besov
spaces that satisfy what we call the multiplier inclusion
condition any bounded column multiplication operator induces a bounded row multiplication operator
. For the Drury-Arveson space
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
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
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?
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
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
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
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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