521 research outputs found
First detailed analysis of multiple system V2083 Cyg
Main aim of this paper is the first detailed analysis of multiple system
V2083 Cyg and to reveal its basic physical properties. The system was studied
by method of the light and radial velocity curves analysis, together with the
interferometric data of the visual pair obtained during a last century. There
was found that the close subsystem contains two very similar stars of spectral
type A7-8. Moreover, the third body is orbiting around this pair with period of
about 177 years. Due to the discrepancy of total mass as derived from two
methods, there arises that the third body is maybe also a binary, or some
object with lower luminosity but higher mass than normal main-sequence star.
Another explanation is that the Hipparcos value of parallax is incorrect and
the system is much closer to the Sun.Comment: 6 pages, 4 figures, published in 2012MNRAS.421.1196
Age and environment affect constitutive immune function in Red Knots (Calidris canutus)
We studied subspecies, age and environmental effects on constitutive immune function (natural antibody and complement titres, haptoglobin activity and leukocyte concentrations) in Red Knots (Calidris canutus). We compared C. c. islandica and C. c. canutus in the Wadden Sea and found no difference in immune function between subspecies. However, C. c. canutus on their wintering grounds in Banc d’Arguin had higher natural antibody and lower complement levels than C. c. canutus or C. c. islandica in the Wadden Sea. This suggests that immune function is determined more by the surrounding environment than by subspecies. We also compared age classes in the Wadden Sea and found that first year birds had significantly lower natural antibody levels than adults, but that second year birds no longer differed from adults. Finally, we examined the interaction of age and environment in Banc d’Arguin. We found that first year birds (but not adults) in a low quality habitat had higher leukocyte concentrations than first year birds or adults in a high quality habitat. Differences in available resources and defence needs between environments, and differences among individuals differentially distributed between sites, are likely important contributors to the variation in immune function we report. Future studies, which examine these factors on wild birds, will be important for our understanding of how animals function in their natural environment.
The effect of neoadjuvant therapy on PD-L1 expression and CD8+lymphocyte density in non-small cell lung cancer.
PD-L1 expression is the routine clinical biomarker for the selection of patients to receive immunotherapy in non-small cell lung cancer (NSCLC). However, the application and best timing of immunotherapy in the resectable setting is still under investigation. We aimed to study the effect of chemotherapy on PD-L1 expression and tumor infiltrating lymphocytes (TILs), which is to date still poorly understood. Our retrospective, single-centre neoadjuvant cohort comprised 96 consecutive patients with NSCLC resected 2000-2016 after neoadjuvant therapy, including paired diagnostic chemo-naïve specimens in 53 cases. A biologically matched surgical cohort of 114 primary resected cases was included. PD-L1 expression, CD8 + TILs density and tertiary lymphoid structures were assessed on whole slides and correlated with clinico-pathological characteristics and survival. Seven/53 and 12/53 cases had lower respectively higher PD-L1 expressions after neoadjuvant therapy. Most cases (n = 34) showed no changes in PD-L1 expression, the majority of these harboring PD-L1 < 1% in both samples (21/34 [61.8%]). Although CD8 + TILs density was significantly higher after chemotherapy (p = 0.031) in resections compared to diagnostic biopsies, this might be due to sampling and statistical bias. No difference in PD-L1 expression or CD8 + TILs density was detected when comparing the neoadjuvant and surgical cohort. In univariable analyses, higher CD8 + TILs density, higher numbers of tertiary lymphoid structures but not PD-L1 expression were significantly associated with longer survival. Increased PD-L1 expression after neoadjuvant chemotherapy was not significantly associated with shorter 5-year survival, but the number of cases was very low. In multivariable analysis, only pT category and age remained independent prognostic factors. In summary, PD-L1 expression was mostly unchanged after neoadjuvant chemotherapy compared to diagnostic biopsies. The sample size of cases with changed PD-L1 expression was too small to draw conclusions on any prognostic value
Estimating Be Star Disk Radii using H-alpha Emission Equivalent Widths
We present numerical models of the circumstellar disks of Be stars, and we
describe the resulting synthetic H-alpha emission lines and maps of the
wavelength-integrated emission flux projected onto the sky. We demonstrate that
there are monotonic relationships between the emission line equivalent width
and the ratio of the angular half-width at half maximum of the projected disk
major axis to the radius of the star. These relationships depend mainly upon
the temperatures of the disk and star, the inclination of the disk normal to
the line of sight, and the adopted outer boundary for the disk radius. We show
that the predicted H-alpha disk radii are consistent with those observed
directly through long baseline interferometry of nearby Be stars (especially
once allowance is made for disk truncation in binaries and for dilution of the
observed H-alpha equivalent width by continuum disk flux in the V-band).Comment: 12 pages, 2 figures, ApJL in pres
Discovery of optically faint obscured quasars with Virtual Observatory tools
We use Virtual Observatory (VO) tools to identify optically faint, obscured
(i.e., type 2) active galactic nuclei (AGN) in the two Great Observatories
Origins Deep Survey (GOODS) fields. By employing publicly available X-ray and
optical data and catalogues we discover 68 type 2 AGN candidates. The X-ray
powers of these sources are estimated by using a previously known correlation
between X-ray luminosity and X-ray-to-optical flux ratio. Thirty-one of our
candidates have high estimated powers (Lx > 10^44 erg/s) and therefore qualify
as optically obscured quasars, the so-called ``QSO 2''. Based on the derived
X-ray powers, our candidates are likely to be at relatively high redshifts, z ~
3, with the QSO 2 at z ~ 4. By going ~ 3 magnitudes fainter than previously
known type 2 AGN in the two GOODS fields we are sampling a region of redshift -
power space which was previously unreachable with classical methods. Our method
brings to 40 the number of QSO 2 in the GOODS fields, an improvement of a
factor ~ 4 when compared to the only 9 such sources previously known. We derive
a QSO 2 surface density down to 10^-15 erg/cm^2/s in the 0.5 - 8 keV band of >~
330/deg^2, ~ 30% of which is made up of previously known sources. This is
larger than current estimates and some predictions and suggests that the
surface density of QSO 2 at faint flux limits has been underestimated. This
work demonstrates that VO tools are mature enough to produce cutting-edge
science results by exploiting astronomical data beyond ``classical''
identification limits (R <~ 25) with interoperable tools for statistical
identification of sources using multiwavelength information.Comment: 16 pages, 6 figures, accepted for publication in Astronomy &
Astrophysics. PDF file with higher resolution figures available at
http://www.eso.org/~ppadovan/AVO-paper.pd
II.5 Where to find the CoRoT data?
This book is dedicated to all the people interested in the CoRoT mission and the beautiful data that were delivered during its six year duration. Either amateurs, professional, young or senior researchers, they will find treasures not only at the time of this publication but also in the future twenty or thirty years. It presents the data in their final version, explains how they have been obtained, how to handle them, describes the tools necessary to understand them, and where to find them. It also highlights the most striking first results obtained up to now. CoRoT has opened several unexpected directions of research and certainly new ones still to be discovered
Introducing BAX: a database for X-ray clusters and groups of galaxies
We present BAX, Base de Donnees Amas de Galaxies X
(http://webast.ast.obs-mip.fr/bax), a multi-wavelength database dedicated to
X-ray clusters and groups of galaxies allowing detailed information retrieval.
BAX is designed to support astronomical research by providing access to
published measurements of the main physical quantities and to the related
bibliographic references: basic data stored in the database are cluster/group
identifiers, equatorial coordinates, redshift, flux, X-ray luminosity (in the
ROSAT band) and temperature, and links to additional linked parameters (in
X-rays, such as spatial profile parameters, as well as SZ parameters of the hot
gas, lensing measurements,and data at other wavelengths, such as optical and
radio). The clusters and groups in BAX can be queried by the basic parameters
as well as the linked parameters or combinations of these. We expect BAX to
become an important tool for the astronomical community. BAX will optimize
various aspects of the scientific analysis of X-ray clusters and groups of
galaxies, from proposal planning to data collection, interpretation and
publication, from both ground based facilities like MEGACAM (CFHT), VIRMOS
(VLT) and space missions like XMM-Newton, Chandra and Planck.Comment: Accepted for publication in Astronomy and Astrophysics Journal.
Contains 4 pages and 1 figur
The CDS information hub
The Centre de Donnees astronomiques de Strasbourg (CDS) provides homogeneousaccess to heterogeneous information of various origins: information aboutastronomical objects in Simbad; catalogs and observation logs in VizieR and inthe catalogue service; reference images and overlays in Aladin; nomenclature inthe Dictionary of Nomenclature; Yellow Page services; the AstroGLU resourcediscovery tool; mirror copies of other reference services; and documentation.With the implementation of links between the CDS services, and with otheron--line reference information, CDS has become a major hub in the rapidlyevolving world of information retrieval in astronomy, developing efficienttools to help astronomers to navigate in the world-wide `Virtual Observatory'under construction, from data in the observatory archives to results publishedin journals. The WWW interface to the CDS services is available at:http://cdsweb.u-strasbg.fr
The heavily polluted atmosphere of the DAZ white dwarf GALEX J193156.8+011745
We report on the discovery of a new heavily polluted white dwarf. The DAZ
white dwarf GALEX J193156.8+011745 was identified in a joint GALEX/GSC survey
of ultraviolet-excess objects. Optical spectra obtained at ESO NTT show strong
absorption lines of magnesium and silicon and a detailed abundance analysis
based on VLT-Kueyen UVES spectra reveal super-solar abundances of silicon and
magnesium, and near-solar abundances of oxygen, calcium, and iron. The overall
abundance pattern bears the signature of ongoing accretion onto the white dwarf
atmosphere. The infrared spectral energy distribution shows an excess in the H
and K bands likely associated with the accretion source.Comment: Accepted for publication in MNRAS Letter
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