8 research outputs found
Asymptotic estimates of the convergence of classical Schwarz waveform relaxation domain decomposition methods for two-dimensional stationary quantum waves
International audienceThis paper is devoted to the analysis of convergence of Schwarz Waveform Relaxation (SWR) domain decomposition methods (DDM) for solving the stationary linear and nonlinear Schrödinger equations by the imaginary-time method. Although SWR are extensively used for numerically solving high-dimensional quantum and classical wave equations, the analysis of convergence and of the rate of convergence is still largely open for variable coefficients linear and nonlinear equations. The aim of this paper is to tackle this problem for both the linear and nonlinear Schrödinger equations in the two-dimensional setting. By extending ideas and concepts presented earlier [12] and by using pseudodifferential calculus, we prove the convergence and determine some approximate rates of convergence of the two-dimensional Classical SWR method for two subdomains with smooth boundary. Some numerical experiments are also proposed to validate the analysis
An Affine-Invariant Sampler for Exoplanet Fitting and Discovery in Radial Velocity Data
Markov Chain Monte Carlo (MCMC) proves to be powerful for Bayesian inference
and in particular for exoplanet radial velocity fitting because MCMC provides
more statistical information and makes better use of data than common
approaches like chi-square fitting. However, the non-linear density functions
encountered in these problems can make MCMC time-consuming. In this paper, we
apply an ensemble sampler respecting affine invariance to orbital parameter
extraction from radial velocity data. This new sampler has only one free
parameter, and it does not require much tuning for good performance, which is
important for automatization. The autocorrelation time of this sampler is
approximately the same for all parameters and far smaller than
Metropolis-Hastings, which means it requires many fewer function calls to
produce the same number of independent samples. The affine-invariant sampler
speeds up MCMC by hundreds of times compared with Metropolis-Hastings in the
same computing situation. This novel sampler would be ideal for projects
involving large datasets such as statistical investigations of planet
distribution. The biggest obstacle to ensemble samplers is the existence of
multiple local optima; we present a clustering technique to deal with local
optima by clustering based on the likelihood of the walkers in the ensemble. We
demonstrate the effectiveness of the sampler on real radial velocity data.Comment: 24 pages, 7 figures, accepted to Ap
A High Eccentricity Component in the Double Planet System Around HD 163607 and a Planet Around HD 164509
We report the detection of three new exoplanets from Keck Observatory. HD
163607 is a metal-rich G5IV star with two planets. The inner planet has an
observed orbital period of 75.29 0.02 days, a semi-amplitude of 51.1
1.4 \ms, an eccentricity of 0.73 0.02 and a derived minimum mass of
\msini = 0.77 0.02 \mjup. This is the largest eccentricity of any known
planet in a multi-planet system. The argument of periastron passage is 78.7
2.0; consequently, the planet's closest approach to its parent
star is very near the line of sight, leading to a relatively high transit
probability of 8%. The outer planet has an orbital period of 3.60 0.02
years, an orbital eccentricity of 0.12 0.06 and a semi-amplitude of 40.4
1.3 \ms. The minimum mass is \msini = 2.29 0.16 \mjup. HD 164509 is
a metal-rich G5V star with a planet in an orbital period of 282.4 3.8
days and an eccentricity of 0.26 0.14. The semi-amplitude of 14.2
2.7 \ms\ implies a minimum mass of 0.48 0.09 \mjup. The radial velocities
of HD 164509 also exhibit a residual linear trend of -5.1 0.7 \ms\ per
year, indicating the presence of an additional longer period companion in the
system. Photometric observations demonstrate that HD 163607 and HD 164509 are
constant in brightness to sub-millimag levels on their radial velocity periods.
This provides strong support for planetary reflex motion as the cause of the
radial velocity variations.Comment: 10 pages, 8 figures, accepted to Ap
Expansion of the Ion Library for Mining SWATH-MS Data through Fractionation Proteomics
The strategy of sequential window
acquisition of all theoretical
fragment ion spectra (SWATH) is emerging in the field of label-free
proteomics. A critical consideration for the processing of SWATH data
is the quality of the ion library (or mass spectrometric reference
map). As the availability of open spectral libraries that can be used
to process SWATH data is limited, most users currently create their
libraries in-house. Herein, we propose an approach to construct an
expanded ion library using the data-dependent acquisition (DDA) data
generated by fractionation proteomics. We identified three critical
elements for achieving a satisfactory ion library during the iterative
process of our ion library expansion, including a correction of the
retention times (RTs) gained from fractionation proteomics, appropriate
integrations of the fractionated proteomics into an ion library, and
assessments of the impact of the expanded ion libraries to data mining
in SWATH. Using a bacterial lysate as an evaluation material, we employed
sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE)
to fractionate the lysate proteins and constructed the expanded ion
library using the fractionation proteomics data. Compared with the
ion library built from the unfractionated proteomics, approximately
20% more peptides were extracted from the expanded ion library. The
extracted peptides, moreover, were acceptable for further quantitative
analysis