109,175 research outputs found
A Circular Statistical Method for Extracting Rotation Measures
We propose a new method for the extraction of Rotation Measure from spectral
polarization data. The method is based on maximum likelihood analysis and takes
into account the circular nature of the polarization data. The method is
unbiased and statistically more efficient than the standard procedure.
We also find that the method is computationally much faster than the standard
procedure if the number of data points are very large.Comment: 17 pages, 5 figure
A statistical method to determine open cluster metallicities
The study of open cluster metallicities helps to understand the local stellar
formation and evolution throughout the Milky Way. Its metallicity gradient is
an important tracer for the Galactic formation in a global sense. Because open
clusters can be treated in a statistical way, the error of the cluster mean is
minimized. Our final goal is a semi-automatic statistical robust method to
estimate the metallicity of a statistically significant number of open clusters
based on Johnson BV data of their members, an algorithm that can easily be
extended to other photometric systems for a systematic investigation. This
method incorporates evolutionary grids for different metallicities and a
calibration of the effective temperature and luminosity. With cluster
parameters (age, reddening and distance) it is possible to estimate the
metallicity from a statistical point of view. The iterative process includes an
intrinsic consistency check of the starting input parameters and allows us to
modify them. We extensively tested the method with published data for the
Hyades and selected sixteen open clusters within 1000pc around the Sun with
available and reliable Johnson BV measurements. In addition, Berkeley 29, with
a distance of about 15kpc was chosen. For several targets we are able to
compare our result with published ones which yielded a very good coincidence
(including Berkeley 29).Comment: 14 pages, 6 figures, accepted for publication in Astronomy &
Astrophysic
New statistical method identifes cytokines that distinguish stool microbiomes
Regressing an outcome or dependent variable onto a set of input or independent variables allows the analyst to measure associations between the two so that changes in the outcome can be described by and predicted by changes in the inputs. While there are many ways of doing this in classical statistics, where the dependent variable has certain properties (e.g., a scalar, survival time, count), little progress on regression where the dependent variable are microbiome taxa counts has been made that do not impose extremely strict conditions on the data. In this paper, we propose and apply a new regression model combining the Dirichlet-multinomial distribution with recursive partitioning providing a fully non-parametric regression model. This model, called DM-RPart, is applied to cytokine data and microbiome taxa count data and is applicable to any microbiome taxa count/metadata, is automatically fit, and intuitively interpretable. This is a model which can be applied to any microbiome or other compositional data and software (R package HMP) available through the R CRAN website
Log-based Anomaly Detection of CPS Using a Statistical Method
Detecting anomalies of a cyber physical system (CPS), which is a complex
system consisting of both physical and software parts, is important because a
CPS often operates autonomously in an unpredictable environment. However,
because of the ever-changing nature and lack of a precise model for a CPS,
detecting anomalies is still a challenging task. To address this problem, we
propose applying an outlier detection method to a CPS log. By using a log
obtained from an actual aquarium management system, we evaluated the
effectiveness of our proposed method by analyzing outliers that it detected. By
investigating the outliers with the developer of the system, we confirmed that
some outliers indicate actual faults in the system. For example, our method
detected failures of mutual exclusion in the control system that were unknown
to the developer. Our method also detected transient losses of functionalities
and unexpected reboots. On the other hand, our method did not detect anomalies
that were too many and similar. In addition, our method reported rare but
unproblematic concurrent combinations of operations as anomalies. Thus, our
approach is effective at finding anomalies, but there is still room for
improvement
A statistical method to estimate low-energy hadronic cross sections
In this article we propose a model based on the Statistical Bootstrap
approach to estimate the cross sections of different hadronic reactions up to a
few GeV in c.m.s energy. The method is based on the idea, when two particles
collide a so called fireball is formed, which after a short time period decays
statistically into a specific final state. To calculate the probabilities we
use a phase space description extended with quark combinatorial factors and the
possibility of more than one fireball formation. In a few simple cases the
probability of a specific final state can be calculated analytically, where we
show that the model is able to reproduce the ratios of the considered cross
sections. We also show that the model is able to describe proton\,-\,antiproton
annihilation at rest. In the latter case we used a numerical method to
calculate the more complicated final state probabilities. Additionally, we
examined the formation of strange and charmed mesons as well, where we used
existing data to fit the relevant model parameters.Comment: 12 pages, 12 figures, submitted to EPJ
A statistical method to estimate low-energy hadronic cross sections
In this article we propose a model based on the Statistical Bootstrap
approach to estimate the cross sections of different hadronic reactions up to a
few GeV in c.m.s energy. The method is based on the idea, when two particles
collide a so called fireball is formed, which after a short time period decays
statistically into a specific final state. To calculate the probabilities we
use a phase space description extended with quark combinatorial factors and the
possibility of more than one fireball formation. In a few simple cases the
probability of a specific final state can be calculated analytically, where we
show that the model is able to reproduce the ratios of the considered cross
sections. We also show that the model is able to describe proton\,-\,antiproton
annihilation at rest. In the latter case we used a numerical method to
calculate the more complicated final state probabilities. Additionally, we
examined the formation of strange and charmed mesons as well, where we used
existing data to fit the relevant model parameters.Comment: 12 pages, 12 figures, submitted to EPJ
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