38,676 research outputs found
On the choice of parameters in solar structure inversion
The observed solar p-mode frequencies provide a powerful diagnostic of the
internal structure of the Sun and permit us to test in considerable detail the
physics used in the theory of stellar structure. Amongst the most commonly used
techniques for inverting such helioseismic data are two implementations of the
optimally localized averages (OLA) method, namely the Subtractive Optimally
Localized Averages (SOLA) and Multiplicative Optimally Localized Averages
(MOLA). Both are controlled by a number of parameters, the proper choice of
which is very important for a reliable inference of the solar internal
structure. Here we make a detailed analysis of the influence of each parameter
on the solution and indicate how to arrive at an optimal set of parameters for
a given data set.Comment: 14 pages, 15 figures. Accepted for publication on MNRA
Recommended from our members
The Warburg Dance Movement Library-The WADAMO Library: A Validation Study
The Warburg Dance Movement Library is a validated set of 234 video clips of dance movements for empirical research in the fields of cognitive science and neuroscience of action perception, affect perception and neuroaesthetics. The library contains two categories of video clips of dance movement sequences. Of each pair, one version of the movement sequence is emotionally expressive (Clip a), while the other version of the same sequence (Clip b) is not expressive but as technically correct as the expressive version (Clip a). We sought to complement previous dance video stimuli libraries. Facial information, colour and music have been removed, and each clip has been faded in and out. We equalised stimulus length (6 seconds, 8 counts in dance theory), the dancers’ clothing and video background and included both male and female dancers, and we controlled for technical correctness of movement execution. The Warburg Dance Movement Library contains both contemporary and ballet movements. Two online surveys (N = 160) confirmed the classification into the two categories of expressivity. Four additional online surveys (N = 80) provided beauty and liking ratings for each clip. A correlation matrix illustrates all variables of this norming study (technical correctness, expressivity, beauty, liking, luminance, motion energy)
Photometric redshift of the GRB 981226 host galaxy
No optical afterglow was found for the dark burst GRB 981226 and hence no
absorption redshift has been obtained. We here use ground-based and space
imaging observations to analyse the spectral energy distribution (SED) of the
host galaxy. By comparison with synthetic template spectra we determine the
photometric redshift of the GRB 981226 host to be z_phot = 1.11+/-0.06 (68%
confidence level). While the age-metallicity degeneracy for the host SED
complicates the determination of accurate ages, metallicity, and extinction,
the photometric redshift is robust. The inferred z_phot value is also robust
compared to a Bayesian redshift estimator which gives z_phot=0.94+/-0.13. The
characteristics for this host are similar to other GRB hosts previously
examined. Available low resolution spectra show no emission lines at the
expected wavelengths. The photometric redshift estimate indicates an isotropic
energy release consistent with the Amati relation for this GRB which had a
spectrum characteristic of an X-ray flash.Comment: Accepted for publication in ApJ Letter
ADIPLS -- the Aarhus adiabatic oscillation package
Development of the Aarhus adiabatic pulsation code started around 1978.
Although the main features have been stable for more than a decade, development
of the code is continuing, concerning numerical properties and output. The code
has been provided as a generally available package and has seen substantial use
at a number of installations. Further development of the package, including
bringing the documentation closer to being up to date, is planned as part of
the HELAS Coordination Action.Comment: Astrophys. Space Sci., in the pres
Nullspaces and frames
In this paper we give new characterizations of Riesz and conditional Riesz
frames in terms of the properties of the nullspace of their synthesis
operators. On the other hand, we also study the oblique dual frames whose
coefficients in the reconstruction formula minimize different weighted norms.Comment: 16 page
- …