22,143 research outputs found
Deep optical observations of the interaction of the SS 433 microquasar jet with the W 50 radio continuum shell
Four mosaics of deep, continuum-subtracted, CCD images have been obtained
over the extensive galactic radio continuum shell, W 50, which surrounds the
remarkable stellar system SS 433. Two of these mosaics in the Halpha+[N II] and
[O III] 5007 A emission lines respectively cover a field of ~2.3 x 2.5 degr^2
which contains all of W 50 but at a low angular resolution of 5 arcsec. The
third and fourth mosaics cover the eastern (in [O III] 5007 A) and western (in
Halpha+[N II]) filamentary nebulosity respectively but at an angular resolution
of 1 arcsec. These observations are supplemented by new low dispersion spectra
and longslit, spatially resolved echelle spectra. The [O III] 5007 A images
show for the first time the distribution of this emission in both the eastern
and western filaments while new Halpha+[N II] emission features are also found
in both of these regions. Approaching flows of faintly emitting material from
the bright eastern filaments of up 100 km/s in radial velocity are detected.
The present observations also suggest that the heliocentric systemic radial
velocity of the whole system is 56+-2 km/s. Furthermore, very deep imagery and
high resolution spectroscopy of a small part of the northern radio ridge of W
50 has revealed for the first time the very faint optical nebulosity associated
with this edge. It is suggested that patchy foreground dust along the ~5 kpc
sightline is inhibiting the detection of all of the optical nebulosity
associated with W 50. The interaction of the microquasar jets of SS 433 with
the W 50 shell is discussed.Comment: 19 pages, 13 figures, 2 tables. Accepted for pubication in MNRA
Plane-extraction from depth-data using a Gaussian mixture regression model
We propose a novel algorithm for unsupervised extraction of piecewise planar
models from depth-data. Among other applications, such models are a good way of
enabling autonomous agents (robots, cars, drones, etc.) to effectively perceive
their surroundings and to navigate in three dimensions. We propose to do this
by fitting the data with a piecewise-linear Gaussian mixture regression model
whose components are skewed over planes, making them flat in appearance rather
than being ellipsoidal, by embedding an outlier-trimming process that is
formally incorporated into the proposed expectation-maximization algorithm, and
by selectively fusing contiguous, coplanar components. Part of our motivation
is an attempt to estimate more accurate plane-extraction by allowing each model
component to make use of all available data through probabilistic clustering.
The algorithm is thoroughly evaluated against a standard benchmark and is shown
to rank among the best of the existing state-of-the-art methods.Comment: 11 pages, 2 figures, 1 tabl
S-cone signals invisible to the motion system can improve motion extraction via grouping by color
Peer reviewedPublisher PD
Assessment of algorithms for mitosis detection in breast cancer histopathology images
The proliferative activity of breast tumors, which is routinely estimated by counting of mitotic figures in hematoxylin and eosin stained histology sections, is considered to be one of the most important prognostic markers. However, mitosis counting is laborious, subjective and may suffer from low inter-observer agreement. With the wider acceptance of whole slide images in pathology labs, automatic image analysis has been proposed as a potential solution for these issues.
In this paper, the results from the Assessment of Mitosis Detection Algorithms 2013 (AMIDA13) challenge are described. The challenge was based on a data set consisting of 12 training and 11 testing subjects, with more than one thousand annotated mitotic figures by multiple observers. Short descriptions and results from the evaluation of eleven methods are presented. The top performing method has an error rate that is comparable to the inter-observer agreement among pathologists
Multivariable proportional-integral-plus (PIP) control of the ALSTOM nonlinear gasifier simulation
Multivariable proportional-integral-plus (PIP) control methods are applied to the nonlinear ALSTOM Benchmark Challenge II. The approach utilises a data-based combined model reduction and linearisation step, which plays an essential role in satisfying the design specifications. The discrete-time transfer function models obtained in this manner are represented in a non-minimum state space form suitable for PIP control system design. Here, full state variable feedback control can be implemented directly from the measured input and output signals of the controlled process, without resorting to the design and implementation of a deterministic state reconstructor or a stochastic Kalman filter. Furthermore, the non-minimal formulation provides more design freedom than the equivalent minimal case, a characteristic that proves particularly useful in tuning the algorithm to meet the Benchmark specifications. The latter requirements are comfortably met for all three operating conditions by using a straightforward to implement, fixed gain, linear PIP algorithm
Left ventricular diastolic function in relation to the urinary proteome: a proof-of-concept study in a general population
Background:
In previous studies, we identified two urinary proteomic classifiers, termed HF1 and HF2, which discriminated subclinical diastolic left ventricular (LV) dysfunction from normal. HF1 and HF2 combine information from 85 and 671 urinary peptides, mainly up- or down-regulated collagen fragments. We sought to validate these classifiers in a population study.
Methods:
In 745 people randomly recruited from a Flemish population (49.8Â years; 51.3% women), we measured early and late diastolic peak velocities of mitral inflow (E and A) and mitral annular velocities (e' and a') by conventional and tissue Doppler echocardiography, and the urinary proteome by capillary electrophoresis coupled with mass spectrometry.
Results:
In the analyses adjusted for sex, age, body mass index, blood pressure, heart rate, LV mass index and intake of medications, we expressed effect sizes per 1-SD increment in the classifiers. HF1 was associated with 0.204 cm/s lower e' peak velocity (95% confidence interval, 0.057â0.351; p = 0.007) and 0.145 higher E/e' ratio (0.023â0.268; p = 0.020), while HF2 was associated with a 0.174 higher E/e' ratio (0.046â0.302; p = 0.008). According to published definitions, 67 (9.0%) participants had impaired LV relaxation and 96 (12.9%) had elevated LV filling pressure. The odds of impaired relaxation associated with HF1 was 1.38 (1.01â1.88; p = 0.043) and that of increased LV filling pressure associated with HF2 was 1.38 (1.00â1.90; p = 0.052).
Conclusions:
In a general population, the urinary proteome correlated with diastolic LV dysfunction, proving its utility for early diagnosis of this condition
SNANA: A Public Software Package for Supernova Analysis
We describe a general analysis package for supernova (SN) light curves,
called SNANA, that contains a simulation, light curve fitter, and cosmology
fitter. The software is designed with the primary goal of using SNe Ia as
distance indicators for the determination of cosmological parameters, but it
can also be used to study efficiencies for analyses of SN rates, estimate
contamination from non-Ia SNe, and optimize future surveys. Several SN models
are available within the same software architecture, allowing technical
features such as K-corrections to be consistently used among multiple models,
and thus making it easier to make detailed comparisons between models. New and
improved light-curve models can be easily added. The software works with
arbitrary surveys and telescopes and has already been used by several
collaborations, leading to more robust and easy-to-use code. This software is
not intended as a final product release, but rather it is designed to undergo
continual improvements from the community as more is learned about SNe. Below
we give an overview of the SNANA capabilities, as well as some of its
limitations. Interested users can find software downloads and more detailed
information from the manuals at http://www.sdss.org/supernova/SNANA.html .Comment: Accepted for publication in PAS
Frequency Tracking and Parameter Estimation for Robust Quantum State-Estimation
In this paper we consider the problem of tracking the state of a quantum
system via a continuous measurement. If the system Hamiltonian is known
precisely, this merely requires integrating the appropriate stochastic master
equation. However, even a small error in the assumed Hamiltonian can render
this approach useless. The natural answer to this problem is to include the
parameters of the Hamiltonian as part of the estimation problem, and the full
Bayesian solution to this task provides a state-estimate that is robust against
uncertainties. However, this approach requires considerable computational
overhead. Here we consider a single qubit in which the Hamiltonian contains a
single unknown parameter. We show that classical frequency estimation
techniques greatly reduce the computational overhead associated with Bayesian
estimation and provide accurate estimates for the qubit frequencyComment: 6 figures, 13 page
- âŠ