2,306 research outputs found
Genralized Robustness of Entanglement
The robustness of entanglement results of Vidal and Tarrach considered the
problem whereby an entangled state is mixed with a separable state so that the
overall state becomes non-entangled. In general it is known that there are also
cases when entangled states are mixed with other entangled states and where the
sum is separable. In this paper, we treat the more general case where entangled
states can be mixed with any states so that the resulting mixture is
unentangled. It is found that entangled pure states for this generalized case
have the same robustness as the restricted case of Vidal and Tarrach.Comment: Final version. Editorial changes and references added to independent
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A Slowly Precessing Disk in the Nucleus of M31 as the Feeding Mechanism for a Central Starburst
We present a kinematic study of the nuclear stellar disk in M31 at infrared
wavelengths using high spatial resolution integral field spectroscopy. The
spatial resolution achieved, FWHM = 0."12 (0.45 pc at the distance of M31), has
only previously been equaled in spectroscopic studies by space-based long-slit
observations. Using adaptive optics-corrected integral field spectroscopy from
the OSIRIS instrument at the W. M. Keck Observatory, we map the line-of-sight
kinematics over the entire old stellar eccentric disk orbiting the supermassive
black hole (SMBH) at a distance of r<4 pc. The peak velocity dispersion is
381+/-55 km/s , offset by 0.13 +/- 0.03 from the SMBH, consistent with previous
high-resolution long-slit observations. There is a lack of near-infrared (NIR)
emission at the position of the SMBH and young nuclear cluster, suggesting a
spatial separation between the young and old stellar populations within the
nucleus. We compare the observed kinematics with dynamical models from Peiris &
Tremaine (2003). The best-fit disk orientation to the NIR flux is [,
, ] = [-33 +/- 4, 44 +/- 2, -15 +/-
15], which is tilted with respect to both the larger-scale galactic
disk and the best-fit orientation derived from optical observations. The
precession rate of the old disk is = 0.0 +/- 3.9 km/s/pc, lower than
the majority of previous observations. This slow precession rate suggests that
stellar winds from the disk will collide and shock, driving rapid gas inflows
and fueling an episodic central starburst as suggested in Chang et al. (2007).Comment: accepted by Ap
On the Numerical Study of the Complexity and Fractal Dimension of CMB Anisotropies
We consider the problem of numerical computation of the Kolmogorov complexity
and the fractal dimension of the anisotropy spots of Cosmic Microwave
Background (CMB) radiation. Namely, we describe an algorithm of estimation of
the complexity of spots given by certain pixel configuration on a grid and
represent the results of computations for a series of structures of different
complexity. Thus, we demonstrate the calculability of such an abstract
descriptor as the Kolmogorov complexity for CMB digitized maps. The correlation
of complexity of the anisotropy spots with their fractal dimension is revealed
as well. This technique can be especially important while analyzing the data of
the forthcoming space experiments.Comment: LATEX, 3 figure
Mobile radio interferometric geodetic systems
Operation of the Astronomical Radio Interferometric Earth Surveying (ARIES) in a proof of concept mode is discussed. Accuracy demonstrations over a short baseline, a 180 km baseline, and a 380 km baseline are documented. Use of ARIES in the Sea Slope Experiment of the National Geodetic Survey to study the apparent differences between oceanographic and geodetic leveling determinations of the sea surface along the Pacific Coast is described. Intergration of the NAVSTAR Global Positioning System and a concept called SERIES (Satellite Emission Radio Interferometric Earth Surveying) is briefly reviewed
Methods to improve recruitment to randomised controlled trials : Cochrane systematic review and meta-analysis
Peer reviewedPublisher PD
Do In-Vehicle Advance Signs Benefit Older and Younger Driver Intersection Performance?
An experimental study was conducted to determine if intersection behavior of those 18 to 24 and 65+ benefited from advanced in-vehicle signs presented in a head-up display (HUD) format. The University of Calgary Driving Simulator (UCDS) was used to determine whether intersection performance improved in the presence of several advanced signs or whether unwanted adaptive behaviors occurred (e.g., increasing speed to run the light instead of stopping). Invehicle signs facilitated an increase in stopping occurrences for both younger and older drivers at intersections with relatively short yellow onsets. In addition, eye movement analysis revealed significant age effects with regard to vertical and horizontal gaze variablity, with younger drivers showing increases in vertical gaze variability compared to the older drivers. Younger drivers also looked more often and had longer percentage of durations fixating on the HUD compared to the older drivers
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