2,041 research outputs found
Towards a fully consistent Milky Way disc model: Part 1 The local model based on kinematic and photometric data
We present a fully consistent evolutionary disc model of the solar cylinder.
The model is based on a sequence of stellar sub-populations described by the
star formation history (SFR) and the dynamical heating law (given by the
age-velocity dispersion relation AVR). The combination of kinematic data from
Hipparcos and the finite lifetimes of main sequence (MS) stars enables us to
determine the detailed vertical disc structure independent of individual
stellar ages and only weakly dependent on the IMF. The disc parameters are
determined by applying a sophisticated best fit algorithm to the MS star
velocity distribution functions in magnitude bins. We find that the AVR is well
constrained by the local kinematics, whereas for the SFR the allowed range is
larger. A simple chemical enrichment model is included in order to fit the
local metallicity distribution of G dwarfs. In our favoured model A the power
law index of the AVR is 0.375 with a minimum and maximum velocity dispersion of
5.1 km/s and 25.0 km/s, respectively. The SFR shows a maximum 10 Gyr ago and
declines by a factor of four to the present day value of 1.5 M_sun/pc^2/Gyr. A
best fit of the IMF leads to power-law indices of -1.46 below and -4.16 above
1.72 M_sun avoiding a kink at 1 M_sun. An isothermal thick disc component with
local density of ~6% of the stellar density is included. A thick disc
containing more than 10% of local stellar mass is inconsistent with the local
kinematics of K and M dwarfs.Comment: 20 pages, 18 figs., accepted by MNRA
HD 69686: A Mysterious High Velocity B Star
We report on the discovery of a high velocity B star, HD 69686. We estimate
its space velocity, distance, surface temperature, gravity, and age. With these
data, we are able to reconstruct the trajectory of the star and to trace it
back to its birthplace. We use evolutionary tracks for single stars to estimate
that HD 69686 was born 73 Myr ago in the outer part of our Galaxy (
kpc) at a position well below the Galactic plane ( kpc), a very
unusual birthplace for a B star. Along the star's projected path in the sky, we
also find about 12 other stars having similar proper motions, and their
photometry data suggest that they are located at the same distance as HD 69686
and probably have the same age. We speculate on the origin of this group by
star formation in a high velocity cloud or as a Galactic merger fragment.Comment: 28 pages, 6 figures, accepted for publication in Ap
Extreme right-wing voting in Western Europe
In this study we explain extreme right-wing voting behaviour in the countries of the European Union and Norway from a micro and macro perspective. Using a multidisciplinary multilevel approach, we take into account individual-level social background characteristics and public opinion alongside country characteristics and characteristics of extreme right-wing parties themselves. By making use of large-scale survey data (N = 49,801) together with country-level statistics and expert survey data, we are able to explain extreme right-wing voting behaviour from this multilevel perspective. Our results show that cross-national differences in support of extreme right-wing parties are particularly due to differences in public opinion on immigration and democracy, the number of non-Western residents in a country and, above all, to party characteristics of the extreme right-wing parties themselves
An XMM-Newton view of the `bare' nucleus of Fairall 9
We present the spectral results from a 130 ks observation, obtained from the
X-ray Multi-Mirror Mission-Newton (XMM-Newton) observatory, of the type I
Seyfert galaxy Fairall 9. An X-ray hardness-ratio analysis of the light-curves,
reveals a `softer-when-brighter' behaviour which is typical for radio-quiet
type I Seyfert galaxies. Moreover, we analyse the high spectral-resolution data
of the reflection grating spectrometer and we did not find any significant
evidence supporting the presence of warm-absorber in the low X-ray energy part
of the source's spectrum. This means that the central nucleus of Fairall 9 is
`clean' and thus its X-ray spectral properties probe directly the physical
conditions of the central engine. The overall X-ray spectrum in the 0.5-10 keV
energy-range, derived from the EPIC data, can be modelled by a relativistically
blurred disc-reflection model. This spectral model yields for Fairall 9 an
intermediate black-hole best-fit spin parameter of
.Comment: Accepted for publication in MNRAS. The paper contains 11 figures and
1 tabl
Fibroblast subsets in non-small cell lung cancer : Associations with survival, mutations, and immune features
Background Cancer-associated fibroblasts (CAFs) are molecularly heterogeneous mesenchymal cells that interact with malignant cells and immune cells and confer anti- and protumorigenic functions. Prior in situ profiling studies of human CAFs have largely relied on scoring single markers, thus presenting a limited view of their molecular complexity. Our objective was to study the complex spatial tumor microenvironment of non-small cell lung cancer (NSCLC) with multiple CAF biomarkers, identify novel CAF subsets, and explore their associations with patient outcome. Methods Multiplex fluorescence immunohistochemistry was employed to spatially profile the CAF landscape in 2 population-based NSCLC cohorts (n = 636) using antibodies against 4 fibroblast markers: platelet-derived growth factor receptor-alpha (PDGFRA) and -beta (PDGFRB), fibroblast activation protein (FAP), and alpha-smooth muscle actin (alpha SMA). The CAF subsets were analyzed for their correlations with mutations, immune characteristics, and clinical variables as well as overall survival. Results Two CAF subsets, CAF7 (PDGFRA-/PDGFRB+/FAP+/alpha SMA+) and CAF13 (PDGFRA+/PDGFRB+/FAP-/alpha SMA+), showed statistically significant but opposite associations with tumor histology, driver mutations (tumor protein p53 [TP53] and epidermal growth factor receptor [EGFR]), immune features (programmed death-ligand 1 and CD163), and prognosis. In patients with early stage tumors (pathological tumor-node-metastasis IA-IB), CAF7 and CAF13 acted as independent prognostic factors. Conclusions Multimarker-defined CAF subsets were identified through high-content spatial profiling. The robust associations of CAFs with driver mutations, immune features, and outcome suggest CAFs as essential factors in NSCLC progression and warrant further studies to explore their potential as biomarkers or therapeutic targets. This study also highlights multiplex fluorescence immunohistochemistry-based CAF profiling as a powerful tool for the discovery of clinically relevant CAF subsets.Peer reviewe
Prevention and early detection of prostate cancer
This Review was sponsored and funded by the International Society of Cancer Prevention (ISCaP), the European Association of Urology (EAU), the National Cancer Institute, USA (NCI) (grant number 1R13CA171707-01), Prostate Cancer UK, Cancer Research UK (CRUK) (grant number C569/A16477), and the Association for International Cancer Research (AICR
Exotic Small Mammals as Potential Reservoirs of Zoonotic Bartonella spp.
To evaluate the risk for emerging human infections caused by zoonotic Bartonella spp. from exotic small mammals, we investigated the prevalence of Bartonella spp. in 546 small mammals (28 species) that had been imported into Japan as pets from Asia, North America, Europe, and the Middle and Near East. We obtained 407 Bartonella isolates and characterized them by molecular phylogenetic analysis of the citrate synthase gene, gltA. The animals examined carried 4 zoonotic Bartonella spp. that cause human endocarditis and neuroretinitis and 6 novel Bartonella spp. at a high prevalence (26.0%, 142/546). We conclude that exotic small mammals potentially serve as reservoirs of several zoonotic Bartonella spp
Micellar Nanoreactors
As clearly described in the series of illustrative examples
reported above, the use of micellar environments in catalysis
is not just a soapy version of homogeneous catalysis.71
Micelles behave much more as nanoreactors characterized
by unique features with all the extra advantages intrinsic
in the use of water as solvent. Micellar catalysis has
been demonstrated to be suitable to almost all classes of
chemical transformations, in particular for a wide range of
reactions promoted by metal complexes or organometallic
species, also with impressive examples in asymmetric
catalysis.
The great advantage of using catalysts already developed
for use in organic media without the need of ligand
modifications to make the catalyst compatible with water,
together with the self-assembling nature of surfactants,
is the key factor for the success of micellar catalysis with
metal species. The surfactant is not just a spectator as
usually the solvent is believed to be, rather it directs the
overall system. A critical balance between catalyst, substrate,
and surfactant properties must be analyzed in detail
in order to ensure high yield, selectivity, and recyclability.
It can be predicted that, thanks to their generally low cost,
surfactants will soon find some applications in large-scale
synthetic methods suitable for industrial applications
Bartonella Spp. in Pets and Effect on Human Health
Pets represent a large reservoir for human infection
Accurate masses and radii of normal stars: modern results and applications
This paper presents and discusses a critical compilation of accurate,
fundamental determinations of stellar masses and radii. We have identified 95
detached binary systems containing 190 stars (94 eclipsing systems, and alpha
Centauri) that satisfy our criterion that the mass and radius of both stars be
known to 3% or better. To these we add interstellar reddening, effective
temperature, metal abundance, rotational velocity and apsidal motion
determinations when available, and we compute a number of other physical
parameters, notably luminosity and distance. We discuss the use of this
information for testing models of stellar evolution. The amount and quality of
the data also allow us to analyse the tidal evolution of the systems in
considerable depth, testing prescriptions of rotational synchronisation and
orbital circularisation in greater detail than possible before. The new data
also enable us to derive empirical calibrations of M and R for single (post-)
main-sequence stars above 0.6 M(Sun). Simple, polynomial functions of T(eff),
log g and [Fe/H] yield M and R with errors of 6% and 3%, respectively.
Excellent agreement is found with independent determinations for host stars of
transiting extrasolar planets, and good agreement with determinations of M and
R from stellar models as constrained by trigonometric parallaxes and
spectroscopic values of T(eff) and [Fe/H]. Finally, we list a set of 23
interferometric binaries with masses known to better than 3%, but without
fundamental radius determinations (except alpha Aur). We discuss the prospects
for improving these and other stellar parameters in the near future.Comment: 56 pages including figures and tables. To appear in The Astronomy and
Astrophysics Review. Ascii versions of the tables will appear in the online
version of the articl
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