61 research outputs found
The intellectual information system of medical aid control in the scope of Russian medical insurance
The article presents the developed intellectual information system, oriented for healthcare providers. The system solves a problem of medical aid quality control in the Russian medical insurance sphere. The main components are ISO13606, fuzzy logic and a case-based reasoning concept. The system provides medical insurance payments forecasting by the analysis of medical records and generates two evaluations based on medical standards and a set of precedents. The result of the system implementation allowed up to a 10% increase in insurance payments for the healthcare provider
Superbubble evolution including the star-forming clouds: Is it possible to reconcile LMC observations with model predictions?
Here we present a possible solution to the apparent discrepancy between the
observed properties of LMC bubbles and the standard, constant density bubble
model. A two-dimensional model of a wind-driven bubble expanding from a
flattened giant molecular cloud is examined. We conclude that the expansion
velocities derived from spherically symmetric models are not always applicable
to elongated young bubbles seen almost face-on due to the LMC orientation. In
addition, an observational test to differentiate between spherical and
elongated bubbles seen face-on is discussed.Comment: 25 pages, 7 figures, accepted to ApJ (September, 1999 issue
Ionized gas velocity dispersion in nearby dwarf galaxies: looking at supersonic turbulent motions
We present the results of ionized gas turbulent motions study in several
nearby dwarf galaxies using a scanning Fabry-Perot interferometer with the 6-m
telescope of the SAO RAS. Combining the `intensity-velocity dispersion'
diagrams (I-sigma) with two-dimensional maps of radial velocity dispersion we
found a number of common patterns pointing to the relation between the value of
chaotic ionized gas motions and processes of current star formation. In five
out of the seven analysed galaxies we identified expanding shells of ionized
gas with diameters of 80-350 pc and kinematic ages of 1-4 Myr. We also
demonstrate that the I-sigma diagrams may be useful for the search of supernova
remnants, other small expanding shells or unique stars in nearby galaxies. As
an example, a candidate luminous blue variable (LBV) was found in UGC 8508. We
propose some additions to the interpretation, previously used by Munoz-Tunon et
al. to explain the I-sigma diagrams for giant star formation regions. In the
case of dwarf galaxies, a major part of the regions with high velocity
dispersion belongs to the diffuse low surface brightness emission, surrounding
the star forming regions. We attribute this to the presence of perturbed low
density gas with high values of turbulent velocities around the giant HII
regions.Comment: 21 pages, 8 figures. Accepted by MNRAS. The high-resolution version
locates at http://www.sao.ru/hq/moisav/MoisLoz_full.pd
Detailed Kinematic Study of the Ionized and Neutral Gas in the Complex of Star Formation in the Galaxy IC 1613
We carried out detailed kinematic studies of the complex of multiple HI and
HII shells that represent the only region of ongoing star formation in the
dwarf irregular galaxy IC 1613. We investigated the ionized-gas kinematics by
using Fabry--Perot H-alpha observations with the 6-m Special Astrophysical
Observatory telescope and the neutral-gas kinematics by using VLA 21-cm radio
observations. We identified three extended (300-350 pc) neutral shells with
which the brightest HII shells in the complex of star formation are associated.
The neutral-gas kinematics in the complex has been studied for the first time
and the H~I shells were found to expand at a velocity of 15--18 km/s. We
constructed velocity ellipses for all HII shells in the complex and refined
(increased) the expansion velocities of most of them. The nature of the
interacting ionized and neutral shells is discussed.Comment: 14 pages, 9 EPS-figure
The Hamburg/SAO survey for low metallicity blue compact/HII-galaxies (HSS-LM). I. The first list of 46 strong-lined galaxies
We present the description and the first results of a new project devoted to
the search for extremely metal-deficient blue compact/HII-galaxies (BCGs) and
to the creation of a well selected large BCG sample with strong emission lines.
Such galaxies should be suitable for reliable determination of their oxygen
abundance through the measurement of the faint [OIII]4363A line. The goals of
the project are two-fold: a) to discover a significant number of new extremely
metal-poor galaxies (Z <= 1/20 Zo), and b) to study the metallicity
distribution of local BCGs. Selection of candidates for follow-up slit
spectroscopy is performed on the database of objective prism spectra of the
Hamburg Quasar Survey. The sky region is limited by delta >= 0 deg. and b^ii <=
-30 deg. In this paper we present the results of the follow-up spectroscopy
conducted with the Russian 6m telescope. The list of observed candidates
contained 52 objects, of which 46 were confirmed as strong-lined BCGs
(EW([OIII]5007) >= 100 A). The remaining five lower excitation ELGs include
three BCGs, and two galaxies classified as SBN (Starburst Nucleus) and DANS
(Dwarf Amorphous Nucleus Starburst). One object is identified as a quasar with
a strong Ly_alpha emission line near 5000 A (z~3). We provide a list with
coordinates, measured radial velocities, B-magnitudes, equivalent widths
EW([OIII]5007) and EW(H_beta) and for the 46 strong-lined BCGs the derived
oxygen abundances 12+log(O/H). The abundances range between 7.42 and 8.4
(corresponding to metallicities between 1/30 and 1/3 Zo). The sample contains
four galaxies with Z < 1/20 Zo, of which three are new discoveries.Comment: 19 pages, 13 figures, accepted for publication in A&A, corrected
typos, reference
The Sensitivity of HAWC to High-Mass Dark Matter Annihilations
The High Altitude Water Cherenkov (HAWC) observatory is a wide field-of-view
detector sensitive to gamma rays of 100 GeV to a few hundred TeV. Located in
central Mexico at 19 degrees North latitude and 4100 m above sea level, HAWC
will observe gamma rays and cosmic rays with an array of water Cherenkov
detectors. The full HAWC array is scheduled to be operational in Spring 2015.
In this paper, we study the HAWC sensitivity to the gamma-ray signatures of
high-mass (multi- TeV) dark matter annihilation. The HAWC observatory will be
sensitive to diverse searches for dark matter annihilation, including
annihilation from extended dark matter sources, the diffuse gamma-ray emission
from dark matter annihilation, and gamma-ray emission from non-luminous dark
matter subhalos. Here we consider the HAWC sensitivity to a subset of these
sources, including dwarf galaxies, the M31 galaxy, the Virgo cluster, and the
Galactic center. We simulate the HAWC response to gamma rays from these sources
in several well-motivated dark matter annihilation channels. If no gamma-ray
excess is observed, we show the limits HAWC can place on the dark matter
cross-section from these sources. In particular, in the case of dark matter
annihilation into gauge bosons, HAWC will be able to detect a narrow range of
dark matter masses to cross-sections below thermal. HAWC should also be
sensitive to non-thermal cross-sections for masses up to nearly 1000 TeV. The
constraints placed by HAWC on the dark matter cross-section from known sources
should be competitive with current limits in the mass range where HAWC has
similar sensitivity. HAWC can additionally explore higher dark matter masses
than are currently constrained.Comment: 15 pages, 4 figures, version to be published in PR
VAMOS: a Pathfinder for the HAWC Gamma-Ray Observatory
VAMOS was a prototype detector built in 2011 at an altitude of 4100m a.s.l.
in the state of Puebla, Mexico. The aim of VAMOS was to finalize the design,
construction techniques and data acquisition system of the HAWC observatory.
HAWC is an air-shower array currently under construction at the same site of
VAMOS with the purpose to study the TeV sky. The VAMOS setup included six water
Cherenkov detectors and two different data acquisition systems. It was in
operation between October 2011 and May 2012 with an average live time of 30%.
Besides the scientific verification purposes, the eight months of data were
used to obtain the results presented in this paper: the detector response to
the Forbush decrease of March 2012, and the analysis of possible emission, at
energies above 30 GeV, for long gamma-ray bursts GRB111016B and GRB120328B.Comment: Accepted for pubblication in Astroparticle Physics Journal (20 pages,
10 figures). Corresponding authors: A.Marinelli and D.Zaboro
Starburst in HS 0822+3542 induced by the very blue LSB dwarf SAO 0822+3545
(Abridged). One of the most metal-deficient blue compact galaxies (BCGs) HS
0822+3542 (Z=1/34 Zsun), is also one of the nearest such objects. A trigger
mechanism for its current SF burst has remained unclear. We report the
discovery of a very blue ((B-V)tot=0.08 and (V-R)tot=0.14) LSB (mu_B^0 > 23.4
arcsec^-2) dwarf irregular (dIrr) galaxy, named SAO 0822+3545. Its small
relative velocity and projected distance of ~11 kpc from the BCG imply their
physical association. For this LSB galaxy, we present spectroscopic results,
total B,V,R magnitudes, the effective radii and surface brightness (SB), and we
describe its morphological properties. We compare the very blue colours of this
dwarf with PEGASE.2 models of the colour evolution of a Z=1/20 Zsun stellar
population, and combine this analysis with the data on the LSBD EW(Ha) values.
The models best describing all available observational data depend on the
relative fraction of massive stars in the IMF used. For a Salpeter IMF with Mup
= 120 Msun, the best model includes a "young" single stellar population (SSP)
with an age of ~10 Myr and an "old" SSP with the age of ~0.2--10 Gyr. The mass
ratio of the old to young components should be in the range of 10 to 30. The
role of interaction in triggering the galaxies major SF episodes during the
last ~100-200 Myr is discussed. For the BCG, based on the spectroscopy with the
6m telescope, we estimate the physical parameters of its SF region and present
the first evidence of an ionized gas supershell. This pair of dwarfs lies deep
within the nearby Lynx-Cancer void, with the nearest bright (L > L*) galaxies
at distances > 3 Mpc. This is probably one of the main factors responsible for
the unevolved state of HS 0822+3542.Comment: 17 pages, 9 figures, accepted to A&
Superbubbles and Energetic Particles in the Galaxy. I: Collective effects of particle acceleration
Observations indicate that most massive stars in the Galaxy appear in groups,
called OB associations, where their strong wind activity generates large
structures known as superbubbles, inside which the subsequent supernovae (SNe)
explode, in tight space and time correlation. Acknowledging this fact, we
investigate four main questions: 1) does the clustering of massive stars and SN
explosions influence the particle acceleration process usually associated with
SNe, and induce collective effects which would not manifest around isolated
supernova remnants?; 2) does it make a difference for the general phenomenology
of Galactic Cosmic Rays (GCRs), notably for their energy spectrum and
composition?; 3) can this help alleviate some of the problems encountered
within the standard GCR source model?; and 4) Is the link between superbubbles
and energetic particles supported by observational data, and can it be further
tested and constrained? We argue for a positive answer to all these questions.
Theoretical, phenomenological and observational aspects are treated in separate
papers. Here, we discuss the interaction of massive stellar winds and SN shocks
inside superbubbles and indicate how this leads to specific acceleration
effects. We also show that due to the high SN explosion rate and low diffusion
coefficient, low-energy particles experience repeated shock acceleration inside
superbubbles.Comment: 14 pages, accepted for publication in A&
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