868 research outputs found
Quantum resource estimates for computing elliptic curve discrete logarithms
We give precise quantum resource estimates for Shor's algorithm to compute
discrete logarithms on elliptic curves over prime fields. The estimates are
derived from a simulation of a Toffoli gate network for controlled elliptic
curve point addition, implemented within the framework of the quantum computing
software tool suite LIQ. We determine circuit implementations for
reversible modular arithmetic, including modular addition, multiplication and
inversion, as well as reversible elliptic curve point addition. We conclude
that elliptic curve discrete logarithms on an elliptic curve defined over an
-bit prime field can be computed on a quantum computer with at most qubits using a quantum circuit of at most Toffoli gates. We are able to classically simulate the
Toffoli networks corresponding to the controlled elliptic curve point addition
as the core piece of Shor's algorithm for the NIST standard curves P-192,
P-224, P-256, P-384 and P-521. Our approach allows gate-level comparisons to
recent resource estimates for Shor's factoring algorithm. The results also
support estimates given earlier by Proos and Zalka and indicate that, for
current parameters at comparable classical security levels, the number of
qubits required to tackle elliptic curves is less than for attacking RSA,
suggesting that indeed ECC is an easier target than RSA.Comment: 24 pages, 2 tables, 11 figures. v2: typos fixed and reference added.
ASIACRYPT 201
Speaker-independent emotion recognition exploiting a psychologically-inspired binary cascade classification schema
In this paper, a psychologically-inspired binary cascade classification schema is proposed for speech emotion recognition. Performance is enhanced because commonly confused pairs of emotions are distinguishable from one another. Extracted features are related to statistics of pitch, formants, and energy contours, as well as spectrum, cepstrum, perceptual and temporal features, autocorrelation, MPEG-7 descriptors, Fujisakis model parameters, voice quality, jitter, and shimmer. Selected features are fed as input to K nearest neighborhood classifier and to support vector machines. Two kernels are tested for the latter: Linear and Gaussian radial basis function. The recently proposed speaker-independent experimental protocol is tested on the Berlin emotional speech database for each gender separately. The best emotion recognition accuracy, achieved by support vector machines with linear kernel, equals 87.7%, outperforming state-of-the-art approaches. Statistical analysis is first carried out with respect to the classifiers error rates and then to evaluate the information expressed by the classifiers confusion matrices. © Springer Science+Business Media, LLC 2011
Voluntarily reported prescribing, monitoring and medication transfer errors in intensive care units in The Netherlands
Background Medication errors occur frequently in intensive care units (ICU). Voluntarily reported medication errors form an easily available source of information. Objective This study aimed to characterize prescribing, monitoring and medication transfer errors that were voluntarily reported in the ICU, in order to reveal medication safety issues. Setting This retrospective data analysis study included reports of medication errors from eleven Dutch ICU's from January 2016 to December 2017. Method We used data extractions from the incident reporting systems of the participating ICU's. The reports were transferred into one database and categorized into type of error, cause, medication (groups), and patient harm. Descriptive statistics were used to calculate the proportion of medication errors and the distribution of subcategories. Based on the analysis, ICU medication safety issues were revealed. Main outcome measure The main outcome measure was the proportion of prescribing, monitoring and medication transfer error reports. Results Prescribing errors were reported most frequently (n = 233, 33%), followed by medication transfer errors (n = 85, 12%) and monitoring errors (n = 27, 4%). Other findings were: medication transfer errors frequently caused serious harm, especially the omission of home medication involving the central nervous system and proton pump inhibitors; omissions and dosing errors occurred most frequently; protocol problems caused a quarter of the medication errors; and medications needing blood level monitoring (e.g. tacrolimus, vancomycin, heparin and insulin) were frequently involved. Conclusion This analysis of voluntarily reported prescribing, monitoring and medication transfer errors warrants several improvement measures in these processes, which may help to increase medication safety in the ICU
Disentangling Baryons and Dark Matter in the Spiral Gravitational Lens B1933+503
Measuring the relative mass contributions of luminous and dark matter in
spiral galaxies is important for understanding their formation and evolution.
The combination of a galaxy rotation curve and strong lensing is a powerful way
to break the disk-halo degeneracy that is inherent in each of the methods
individually. We present an analysis of the 10-image radio spiral lens
B1933+503 at z_l=0.755, incorporating (1) new global VLBI observations, (2) new
adaptive-optics assisted K-band imaging, (3) new spectroscopic observations for
the lens galaxy rotation curve and the source redshift. We construct a
three-dimensionally axisymmetric mass distribution with 3 components: an
exponential profile for the disk, a point mass for the bulge, and an NFW
profile for the halo. The mass model is simultaneously fitted to the kinematics
and the lensing data. The NFW halo needs to be oblate with a flattening of
a/c=0.33^{+0.07}_{-0.05} to be consistent with the radio data. This suggests
that baryons are effective at making the halos oblate near the center. The
lensing and kinematics analysis probe the inner ~10 kpc of the galaxy, and we
obtain a lower limit on the halo scale radius of 16 kpc (95% CI). The dark
matter mass fraction inside a sphere with a radius of 2.2 disk scale lengths is
f_{DM,2.2}=0.43^{+0.10}_{-0.09}. The contribution of the disk to the total
circular velocity at 2.2 disk scale lengths is 0.76^{+0.05}_{-0.06}, suggesting
that the disk is marginally submaximal. The stellar mass of the disk from our
modeling is log_{10}(M_{*}/M_{sun}) = 11.06^{+0.09}_{-0.11} assuming that the
cold gas contributes ~20% to the total disk mass. In comparison to the stellar
masses estimated from stellar population synthesis models, the stellar initial
mass function of Chabrier is preferred to that of Salpeter by a probability
factor of 7.2.Comment: 16 pages, 13 figures, minor revisions based on referee's comments,
accepted for publication in Ap
The Metallicity-Luminosity Relation, Effective Yields, and Metal Loss in Spiral and Irregular Galaxies
I present results on the correlation between galaxy mass, luminosity, and
metallicity for a sample of spiral and irregular galaxies having well-measured
abundance profiles, distances, and rotation speeds. Additional data for low
surface brightness galaxies from the literature are also included for
comparison. These data are combined to study the metallicity-luminosity and
metallicity-rotation speed correlations for spiral and irregular galaxies. The
metallicity luminosity correlation shows its familiar form for these galaxies,
a roughly uniform change in the average present-day O/H abundance of about a
factor 100 over 11 magnitudes in B luminosity. However, the O/H - V(rot)
relation shows a change in slope at a rotation speed of about 125 km/sec. At
faster V(rot), there appears to be no relation between average metallicity and
rotation speed. At lower V(rot), the metallicity correlates with rotation
speed. This change in behavior could be the result of increasing loss of metals
from the smaller galaxies in supernova-driven winds. This idea is tested by
looking at the variation in effective yield, derived from observed abundances
and gas fractions assuming closed box chemical evolution. The effective yields
derived for spiral and irregular galaxies increase by a factor of 10-20 from
V(rot) approximately 5 km/sec to V(rot) approximately 300 km/sec, asympotically
increasing to approximately constant y(eff) for V(rot) > 150 km/sec. The trend
suggests that galaxies with V(rot) < 100-150 km/sec may lose a large fraction
of their SN ejecta, while galaxies above this value tend to retain metals.Comment: 40 pages total, including 7 encapsulated postscript figures. Accepted
for publication in 20 Dec 2002 Ap
Observational Constraints on the Modified Gravity Model (MOG) Proposed by Moffat: Using the Magellanic System
A simple model for the dynamics of the Magellanic Stream (MS), in the
framework of modified gravity models is investigated. We assume that the galaxy
is made up of baryonic matter out of context of dark matter scenario. The model
we used here is named Modified Gravity (MOG) proposed by Moffat (2005). In
order to examine the compatibility of the overall properties of the MS under
the MOG theory, the observational radial velocity profile of the MS is compared
with the numerical results using the fit method. In order to obtain
the best model parameters, a maximum likelihood analysis is performed. We also
compare the results of this model with the Cold Dark Matter (CDM) halo model
and the other alternative gravity model that proposed by Bekenstein (2004), so
called TeVeS. We show that by selecting the appropriate values for the free
parameters, the MOG theory seems to be plausible to explain the dynamics of the
MS as well as the CDM and the TeVeS models.Comment: 14 pages, 3 Figures, accepted in Int. J. Theor. Phy
Rotation Curves of Spiral Galaxies
Rotation curves of spiral galaxies are the major tool for determining the
distribution of mass in spiral galaxies. They provide fundamental information
for understanding the dynamics, evolution and formation of spiral galaxies. We
describe various methods to derive rotation curves, and review the results
obtained. We discuss the basic characteristics of observed rotation curves in
relation to various galaxy properties, such as Hubble type, structure,
activity, and environment.Comment: 40 pages, 6 gif figures; Ann. Rev. Astron. Astrophys. Vol. 39, p.137,
200
WALLABY Pilot Survey: the Potential Polar Ring Galaxies NGC~4632 and NGC~6156
We report on the discovery of two potential polar ring galaxies (PRGs) in the
WALLABY Pilot Data Release 1 (PDR1). These untargetted detections,
cross-matched to NGC 4632 and NGC 6156, are some of the first galaxies where
the Hi observations show two distinct components. We used the iDaVIE virtual
reality software to separate the anomalous gas from the galactic gas and find
that the anomalous gas comprises ~ 50% of the total H i content of both
systems. We have generated plausible 3D kinematic models for each galaxy
assuming that the rings are circular and inclined at 90 degrees to the galaxy
bodies. These models show that the data are consistent with PRGs, but do not
definitively prove that the galaxies are PRGs. By projecting these models at
different combinations of main disk inclinations, ring orientations, and
angular resolutions in mock datacubes, we have further investigated the
detectability of similar PRGs in WALLABY. Assuming that these galaxies are
indeed PRGs, the detectability fraction, combined with the size distribution of
WALLABY PDR1 galaxies, implies an incidence rate of ~ 1% - 3%. If this rate
holds true, the WALLABY survey will detect hundreds of new polar ring galaxies.Comment: Accepted to MNRAS -- Corrected Table
Dynamics of Barred Galaxies
Some 30% of disc galaxies have a pronounced central bar feature in the disc
plane and many more have weaker features of a similar kind. Kinematic data
indicate that the bar constitutes a major non-axisymmetric component of the
mass distribution and that the bar pattern tumbles rapidly about the axis
normal to the disc plane. The observed motions are consistent with material
within the bar streaming along highly elongated orbits aligned with the
rotating major axis. A barred galaxy may also contain a spheroidal bulge at its
centre, spirals in the outer disc and, less commonly, other features such as a
ring or lens. Mild asymmetries in both the light and kinematics are quite
common. We review the main problems presented by these complicated dynamical
systems and summarize the effort so far made towards their solution,
emphasizing results which appear secure. (Truncated)Comment: This old review appeared in 1993. Plain tex with macro file. 82 pages
18 figures. A pdf version with figures at full resolution (3.24MB) is
available at http://www.physics.rutgers.edu/~sellwood/bar_review.pd
Generalized Chaplygin gas model: Cosmological consequences and statefinder diagnosis
The generalized Chaplygin gas (GCG) model in spatially flat universe is
investigated. The cosmological consequences led by GCG model including the
evolution of EoS parameter, deceleration parameter and dimensionless Hubble
parameter are calculated. We show that the GCG model behaves as a general
quintessence model. The GCG model can also represent the pressureless CDM model
at the early time and cosmological constant model at the late time. The
dependency of transition from decelerated expansion to accelerated expansion on
the parameters of model is investigated. The statefinder parameters and
in this model are derived and the evolutionary trajectories in plane are
plotted. Finally, based on current observational data, we plot the evolutionary
trajectories in and planes for best fit values of the parameters of
GCG model. It has been shown that although, there are similarities between GCG
model and other forms of chaplygin gas in statefinder plane, but the distance
of this model from the CDM fixed point in diagram is shorter
compare with standard chaplygin gas model.Comment: 10 pages, 5 figures, accepted in Astrophys Space Sci. (2011
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