1,933 research outputs found
Description of two-electron atoms with correct cusp conditions
New sets of functions with arbitrary large finite cardinality are constructed
for two-electron atoms. Functions from these sets exactly satisfy the Kato's
cusp conditions. The new functions are special linear combinations of
Hylleraas- and/or Kinoshita-type terms. Standard variational calculation,
leading to matrix eigenvalue problem, can be carried out to calculate the
energies of the system. There is no need for optimization with constraints to
satisfy the cusp conditions. In the numerical examples the ground state energy
of the He atom is considered
Thin accretion disks onto brane world black holes
The braneworld description of our universe entails a large extra dimension
and a fundamental scale of gravity that might be lower by several orders of
magnitude as compared to the Planck scale. An interesting consequence of the
braneworld scenario is in the nature of the vacuum solutions of the brane
gravitational field equations, with properties quite distinct as compared to
the standard black hole solutions of general relativity. One possibility of
observationally discriminating between different types of black holes is the
study of the emission properties of the accretion disks. In the present paper
we obtain the energy flux, the emission spectrum and accretion efficiency from
the accretion disks around several classes of static and rotating brane world
black holes, and we compare them to the general relativistic case. Particular
signatures can appear in the electromagnetic spectrum, thus leading to the
possibility of directly testing extra-dimensional physical models by using
astrophysical observations of the emission spectra from accretion disks.Comment: 37 pages, 14 figures, accepted for publication in PR
Direct Identification of the Glass Transition: Growing Length Scale and the Onset of Plasticity
Understanding the mechanical properties of glasses remains elusive since the
glass transition itself is not fully understood, even in well studied examples
of glass formers in two dimensions. In this context we demonstrate here: (i) a
direct evidence for a diverging length scale at the glass transition (ii) an
identification of the glass transition with the disappearance of fluid-like
regions and (iii) the appearance in the glass state of fluid-like regions when
mechanical strain is applied.
These fluid-like regions are associated with the onset of plasticity in the
amorphous solid. The relaxation times which diverge upon the approach to the
glass transition are related quantitatively.Comment: 5 pages, 5 figs.; 2 figs. omitted, new fig., quasi-crystal discussion
omitted, new material on relaxation time
Medium-resolution echelle spectroscopy of pulsating variables and exoplanet host stars with sub-meter telescopes
Here we present two of our interesting results obtained over the last 18
months from spectroscopic monitoring of binary pulsating stars and exoplanet
host stars. Our investigations are very promising by demonstrating that modern
fiber-fed spectrographs open a whole new chapter in the life of small national
and university observatories.Comment: 3 pages, 3 figures. To be published in the proceedings of the
workshop on "Observing techniques, instrumentation and science for
metre-class telescopes", Sep. 2013, Tatranska Lomnica, Slovaki
LPV-based quality interpretations on modeling and control of diabetes
In this study we introduce different novel interpretations in
the case of Linear Parameter Varying (LPV) methodology, which
are directly usable in modeling and control design in diabetes
research. These novel interpretations are based on the
parameter vectors of the LPV parameter space. The theoretical
solutions are demonstrated on a simple, known Type 1 Diabetes
Model used in intensive care
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