11,937 research outputs found
Variable stars in the globular cluster NGC 7492. New discoveries and physical parameters determination
We have performed a photometric V, R, I CCD time-series analysis with a
baseline of ~8 years of the outer-halo globular cluster NGC 7492 with the aim
of searching for new variables and using these (and the previously known
variables) to determine the physical parameters of interest for the cluster
(e.g. metallicity, absolute magnitude of the horizontal branch, distance,
etc.).
We use difference image analysis (DIA) to extract precise light curves in the
relatively crowded star field, especially towards the densely populated central
region. Several approaches are used for variability detection that recover the
known variables and lead to new discoveries. We determine the physical
parameters of the only RR0 star using light curve Fourier decomposition
analysis.
We find one new long period variable and two SX Phe stars in the blue
straggler region. We also present one candidate SX Phe star which requires
follow-up observations. Assuming that the SX Phe stars are cluster members and
using the period-luminosity relation for these stars, we estimate their
distances as ~25.2+-1.8 and 26.8+-1.8 kpc, and identify their possible modes of
oscillation. We refine the periods of the two RR Lyrae stars in our field of
view. We find that the RR1 star V2 is undergoing a period change and possibly
exhibits the Blazhko effect. Fourier decomposition of the light curve of the
RR0 star V1 allows us to estimate the metallicity [Fe/H]_ZW-1.68+-0.10 or
[Fe/H]_UVES-1.64+-0.13, log-luminosity ~1.76+-0.02, absolute magnitude
~0.38+-0.04 mag, and true distance modulus of ~16.93+-0.04 mag, which is
equivalent to a distance of ~24.3+-0.5 kpc. All of these values are consistent
with previous estimates in the literature.Comment: 12 pages, 13 figures, 6 tables, accepted for publication in A&
Constraining the parameters of globular cluster NGC 1904 from its variable star population
We present the analysis of 11 nights of V and I time-series observations of
the globular cluster NGC 1904 (M 79). Using this we searched for variable stars
in this cluster and attempted to refine the periods of known variables, making
use of a time baseline spanning almost 8 years. We use our data to derive the
metallicity and distance of NGC 1904. We used difference imaging to reduce our
data to obtain high-precision light curves of variable stars. We then estimated
the cluster parameters by performing a Fourier decomposition of the light
curves of RR Lyrae stars for which a good period estimate was possible. We also
derive an estimate for the age of the cluster by fitting theoretical isochrones
to our colour-magnitude diagram (CMD). Out of 13 stars previously classified as
variables, we confirm that 10 are bona fide variables. We cannot detect
variability in one other within the precision of our data, while there are two
which are saturated in our data frames, but we do not find sufficient evidence
in the literature to confirm their variability. We also detect a new RR Lyrae
variable, giving a total number of confirmed variable stars in NGC 1904 of 11.
Using the Fourier parameters, we find a cluster metallicity [Fe/H]_ZW=-1.63 +-
0.14, or [Fe/H]_UVES=-1.57 \pm 0.18, and a distance of 13.3 +- 0.4 kpc (using
RR0 variables) or 12.9 kpc (using the one RR1 variable in our sample for which
Fourier decomposition was possible).Comment: 14 pages, 11 figures, accepted for publication in A&
RR Lyrae Stars In The GCVS Observed By The Qatar Exoplanet Survey
We used the light curve archive of the Qatar Exoplanet Survey (QES) to
investigate the RR Lyrae variable stars listed in the General Catalogue of
Variable Stars (GCVS). Of 588 variables studied, we reclassify 14 as eclipsing
binaries, one as an RS Canum Venaticorum-type variable, one as an irregular
variable, four as classical Cepheids, and one as a type II Cepheid, while also
improving their periods. We also report new RR Lyrae sub-type classifications
for 65 variables and improve on the GCVS period estimates for 135 RR Lyrae
variables. There are seven double-mode RR Lyrae stars in the sample for which
we measured their fundamental and first overtone periods. Finally, we detect
the Blazhko effect in 38 of the RR Lyrae stars for the first time and we
successfully measured the Blazhko period for 26 of them.Comment: Accepted IBV
Chronic bacterial prostatitis: efficacy of short-lasting antibiotic therapy with prulifloxacin (Unidrox®) in association with saw palmetto extract, lactobacillus sporogens and arbutin (Lactorepens®)
Bacterial prostatitis (BP) is a common condition accounting responsible for about 5-10% of all prostatitis cases; chronic bacterial prostatitis (CBP) classified as type II, are less common but is a condition that significantly hampers the quality of life, (QoL) because not only is it a physical condition but also a psychological distress. Commonly patients are treated with antibiotics alone, and in particular fluoroquinolones are suggested by the European Urology guidelines. This approach, although recommended, may not be enough. Thus, a multimodal approach to the prolonged antibiotic therapy may be helpful.210 patients affected by chronic bacterial prostatitis were enrolled in the study. All patients were positive to Meares-Stamey test and symptoms duration was > 3 months. The purpose of the study was to evaluate the efficacy of a long lasting therapy with a fluoroquinolone in association with a nutraceutical supplement (prulifloxacin 600 mg for 21 days and an association of Serenoa repens 320 mg, Lactobacillus Sporogens 200 mg, Arbutin 100 mg for 30 days). Patients were randomized in two groups (A and B) receiving respectively antibiotic alone and an association of antibiotic plus supplement.Biological recurrence at 2 months in Group A was observed in 21 patients (27.6%) and in Group B in 6 patients (7.8%). Uropathogens found at the first follow-up were for the majority Gram - (E. coli and Enterobacter spp.). A statistically significant difference was found at the time of the follow-up between Group A and B in the NIH-CPSI questionnaire score, symptoms evidence and serum PSA.Broad band, short-lasting antibiotic therapy in association with a nutritional supplement (serenoa repens, lactobacillus sporogens and arbutin) show better control and recurrence rate on patients affected by chronic bacterial prostatitits in comparison with antibiotic treatment alone.NCT02130713Date of trial Registration: 30/04/2014
GeoCLEF 2007: the CLEF 2007 cross-language geographic information retrieval track overview
GeoCLEF ran as a regular track for the second time within the Cross
Language Evaluation Forum (CLEF) 2007. The purpose of GeoCLEF is to test
and evaluate cross-language geographic information retrieval (GIR): retrieval
for topics with a geographic specification. GeoCLEF 2007 consisted of two sub
tasks. A search task ran for the third time and a query classification task was
organized for the first. For the GeoCLEF 2007 search task, twenty-five search
topics were defined by the organizing groups for searching English, German,
Portuguese and Spanish document collections. All topics were translated into
English, Indonesian, Portuguese, Spanish and German. Several topics in 2007
were geographically challenging. Thirteen groups submitted 108 runs. The
groups used a variety of approaches. For the classification task, a query log
from a search engine was provided and the groups needed to identify the
queries with a geographic scope and the geographic components within the
local queries
Collisional cross sections and momentum distributions in astrophysical plasmas: dynamics and statistical mechanics link
We show that, in stellar core plasmas, the one-body momentum distribution
function is strongly dependent, at least in the high velocity regime, on the
microscopic dynamics of ion elastic collisions and therefore on the effective
collisional cross sections, if a random force field is present. We take into
account two cross sections describing ion-dipole and ion-ion screened
interactions. Furthermore we introduce a third unusual cross section, to link
statistical distributions and a quantum effect originated by the
energy-momentum uncertainty owing to many-body collisions, and propose a
possible physical interpretation in terms of a tidal-like force. We show that
each collisional cross section gives rise to a slight peculiar correction on
the Maxwellian momentum distribution function in a well defined velocity
interval. We also find a possible link between microscopical dynamics of ions
and statistical mechanics interpreting our results in the framework of
non-extensive statistical mechanics.Comment: 8 page
GeoCLEF 2006: the CLEF 2006 Ccross-language geographic information retrieval track overview
After being a pilot track in 2005, GeoCLEF advanced to be a regular track within CLEF 2006. The
purpose of GeoCLEF is to test and evaluate cross-language geographic information retrieval (GIR): retrieval for
topics with a geographic specification. For GeoCLEF 2006, twenty-five search topics were defined by the
organizing groups for searching English, German, Portuguese and Spanish document collections. Topics were
translated into English, German, Portuguese, Spanish and Japanese. Several topics in 2006 were significantly
more geographically challenging than in 2005. Seventeen groups submitted 149 runs (up from eleven groups and
117 runs in GeoCLEF 2005). The groups used a variety of approaches, including geographic bounding boxes,
named entity extraction and external knowledge bases (geographic thesauri and ontologies and gazetteers)
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