2,735 research outputs found
WR 7a: a V Sagittae or a qWR star?
The star WR 7a, also known as SPH 2, has a spectrum that resembles that of V
Sagittae stars although no O VI emission has been reported. The Temporal
Variance Spectrum - TVS - analysis of our data shows weak but strongly variable
emission of O VI lines which is below the noise level in the intensity
spectrum. Contrary to what is seen in V Sagittae stars, optical photometric
monitoring shows very little, if any, flickering. We found evidence of periodic
variability. The most likely photometric period is P(phot) = 0.227(14) d, while
radial velocities suggest a period of P(spec) = 0.204(13) d. One-day aliases of
these periods can not be ruled out. We call attention to similarities with HD
45166 and DI Cru (= WR 46), where multiple periods are present. They may be
associated to the binary motion or to non-radial oscillations. In contrast to a
previous conclusion by Pereira et al. (1998), we show that WR 7a contains
hydrogen. The spectrum of the primary star seems to be detectable as the N V
4604A absorption line is visible. If so, it means that the wind is optically
thin in the continuum and that it is likely to be a helium main sequence star.
Given the similarity to HD 45166, we suggests that WR 7a may be a qWR - quasi
Wolf-Rayet - star. Its classification is WN4h/CE in the Smith et al. (1996)
three dimensional classification system.Comment: 6 pages, 6 figures, preprint of an article accepted for publication
in Monthly Notices of The Royal Astronomical Societ
WX Cen (= WR 48c) - a possible type Ia Supernova progenitor
We confirm the orbital period of WX Cen (WR 48c) determined by Diaz & Steiner
(1995) and refined its value to P = 0.416 961 5 d. The light curve of this
object has an amplitude of 0.32 magnitudes and has a V-shaped narrow minimum,
similar to the ones seen in V Sge, V617 Sgr and in Compact Binary Supersoft
Sources - CBSS. The He II Pickering series decrement shows that the system has
significant amount of hydrogen. The He II 4686 emission lines became weaker
between the 1991 and 2000/2002 observations, indicating distinct levels of
activity. The Balmer lines show variable features with V = -2900 km/s in
absorption and with V = +/- 3500 km/s in emission. These highly variable events
remind the satellites in emission of CBSS. We estimate the color excess as
E(B-V)=0.63. Given the distance-color excess relation in the direction of WX
Cen, this implies a distance of 2.8 kpc. Interstellar absorption of the Na I D
lines show components at -4.1 km/s, which corresponds to the velocity of the
Coalsack, and three other components a -23.9, -32.0 and -39.0 km/s. These
components are also seen with similar strengths in field stars that have
distances between 1.8 and 2.7 kpc. The intrinsic color of WX Cen is (B-V)0=-0.2
and the absolute magnitude, Mv = -0.5. Extended red wings in the strong
emission lines are seen. A possible explanation is that the system has a
spill-over stream similar to what is seen in V617 Sgr. We predict that when
observed in opposite orbital phase, blue wings would be observed. The velocity
of the satellite-like feature is consistent with the idea that the central star
is a white dwarf with a mass of M ~ 0.9 Msun. With the high accretion rate
under consideration, the star may become a SN Ia in a time-scale of 5 X 10^6
years.Comment: 12 pages, 11 EPS figures, preprint of an article accepted for
publication in Monthly Notices of The Royal Astronomical Societ
Chemotherapy-induced oral mucositis is associated with detrimental bacterial dysbiosis.
BACKGROUND: Gastrointestinal mucosal injury (mucositis), commonly affecting the oral cavity, is a clinically significant yet incompletely understood complication of cancer chemotherapy. Although antineoplastic cytotoxicity constitutes the primary injury trigger, the interaction of oral microbial commensals with mucosal tissues could modify the response. It is not clear, however, whether chemotherapy and its associated treatments affect oral microbial communities disrupting the homeostatic balance between resident microorganisms and the adjacent mucosa and if such alterations are associated with mucositis. To gain knowledge on the pathophysiology of oral mucositis, 49 subjects receiving 5-fluorouracil (5-FU) or doxorubicin-based chemotherapy were evaluated longitudinally during one cycle, assessing clinical outcomes, bacterial and fungal oral microbiome changes, and epithelial transcriptome responses. As a control for microbiome stability, 30 non-cancer subjects were longitudinally assessed. Through complementary in vitro assays, we also evaluated the antibacterial potential of 5-FU on oral microorganisms and the interaction of commensals with oral epithelial tissues.
RESULTS: Oral mucositis severity was associated with 5-FU, increased salivary flow, and higher oral granulocyte counts. The oral bacteriome was disrupted during chemotherapy and while antibiotic and acid inhibitor intake contributed to these changes, bacteriome disruptions were also correlated with antineoplastics and independently and strongly associated with oral mucositis severity. Mucositis-associated bacteriome shifts included depletion of common health-associated commensals from the genera Streptococcus, Actinomyces, Gemella, Granulicatella, and Veillonella and enrichment of Gram-negative bacteria such as Fusobacterium nucleatum and Prevotella oris. Shifts could not be explained by a direct antibacterial effect of 5-FU, but rather resembled the inflammation-associated dysbiotic shifts seen in other oral conditions. Epithelial transcriptional responses during chemotherapy included upregulation of genes involved in innate immunity and apoptosis. Using a multilayer epithelial construct, we show mucositis-associated dysbiotic shifts may contribute to aggravate mucosal damage since the mucositis-depleted Streptococcus salivarius was tolerated as a commensal, while the mucositis-enriched F. nucleatum displayed pro-inflammatory and pro-apoptotic capacity.
CONCLUSIONS: Altogether, our work reveals that chemotherapy-induced oral mucositis is associated with bacterial dysbiosis and demonstrates the potential for dysbiotic shifts to aggravate antineoplastic-induced epithelial injury. These findings suggest that control of oral bacterial dysbiosis could represent a novel preventive approach to ameliorate oral mucositis
Susceptibility to heat wave-related mortality: a follow-up study of a cohort of elderly in Rome
Effects of apparent temperature on daily mortality in Lisbon and Oporto, Portugal
<p>Abstract</p> <p>Background</p> <p>Evidence that elevated temperatures can lead to increased mortality is well documented, with population vulnerability being location specific. However, very few studies have been conducted that assess the effects of temperature on daily mortality in urban areas in Portugal.</p> <p>Methods</p> <p>In this paper time-series analysis was used to model the relationship between mean apparent temperature and daily mortality during the warm season (April to September) in the two largest urban areas in Portugal: Lisbon and Oporto. We used generalized additive Poisson regression models, adjusted for day of week and season.</p> <p>Results</p> <p>Our results show that in Lisbon, a 1°C increase in mean apparent temperature is associated with a 2.1% (95%CI: 1.6, 2.5), 2.4% (95%CI: 1.7, 3.1) and 1.7% (95%CI: 0.1, 3.4) increase in all-causes, cardiovascular, and respiratory mortality, respectively. In Oporto the increase was 1.5% (95%CI: 1.0, 1.9), 2.1% (95%CI: 1.3, 2.9) and 2.7% (95%CI: 1.2, 4.3) respectively. In both cities, this increase was greater for the group >65 years.</p> <p>Conclusion</p> <p>Even without extremes in apparent temperature, we observed an association between temperature and daily mortality in Portugal. Additional research is needed to allow for better assessment of vulnerability within populations in Portugal in order to develop more effective heat-related morbidity and mortality public health programs.</p
Search for CP violation in decays
A model-independent search for direct CP violation in the Cabibbo suppressed
decay in a sample of approximately 370,000 decays is
carried out. The data were collected by the LHCb experiment in 2010 and
correspond to an integrated luminosity of 35 pb. The normalized Dalitz
plot distributions for and are compared using four different
binning schemes that are sensitive to different manifestations of CP violation.
No evidence for CP asymmetry is found.Comment: 13 pages, 8 figures, submitted to Phys. Rev.
Measurement of charged particle multiplicities in collisions at TeV in the forward region
The charged particle production in proton-proton collisions is studied with
the LHCb detector at a centre-of-mass energy of TeV in different
intervals of pseudorapidity . The charged particles are reconstructed
close to the interaction region in the vertex detector, which provides high
reconstruction efficiency in the ranges and
. The data were taken with a minimum bias trigger, only requiring
one or more reconstructed tracks in the vertex detector. By selecting an event
sample with at least one track with a transverse momentum greater than 1 GeV/c
a hard QCD subsample is investigated. Several event generators are compared
with the data; none are able to describe fully the multiplicity distributions
or the charged particle density distribution as a function of . In
general, the models underestimate the charged particle production
Search for squarks and gluinos in events with isolated leptons, jets and missing transverse momentum at s√=8 TeV with the ATLAS detector
The results of a search for supersymmetry in final states containing at least one isolated lepton (electron or muon), jets and large missing transverse momentum with the ATLAS detector at the Large Hadron Collider are reported. The search is based on proton-proton collision data at a centre-of-mass energy s√=8 TeV collected in 2012, corresponding to an integrated luminosity of 20 fb−1. No significant excess above the Standard Model expectation is observed. Limits are set on supersymmetric particle masses for various supersymmetric models. Depending on the model, the search excludes gluino masses up to 1.32 TeV and squark masses up to 840 GeV. Limits are also set on the parameters of a minimal universal extra dimension model, excluding a compactification radius of 1/R c = 950 GeV for a cut-off scale times radius (ΛR c) of approximately 30
Measurements of fiducial and differential cross sections for Higgs boson production in the diphoton decay channel at s√=8 TeV with ATLAS
Measurements of fiducial and differential cross sections are presented for Higgs boson production in proton-proton collisions at a centre-of-mass energy of s√=8 TeV. The analysis is performed in the H → γγ decay channel using 20.3 fb−1 of data recorded by the ATLAS experiment at the CERN Large Hadron Collider. The signal is extracted using a fit to the diphoton invariant mass spectrum assuming that the width of the resonance is much smaller than the experimental resolution. The signal yields are corrected for the effects of detector inefficiency and resolution. The pp → H → γγ fiducial cross section is measured to be 43.2 ±9.4(stat.) − 2.9 + 3.2 (syst.) ±1.2(lumi)fb for a Higgs boson of mass 125.4GeV decaying to two isolated photons that have transverse momentum greater than 35% and 25% of the diphoton invariant mass and each with absolute pseudorapidity less than 2.37. Four additional fiducial cross sections and two cross-section limits are presented in phase space regions that test the theoretical modelling of different Higgs boson production mechanisms, or are sensitive to physics beyond the Standard Model. Differential cross sections are also presented, as a function of variables related to the diphoton kinematics and the jet activity produced in the Higgs boson events. The observed spectra are statistically limited but broadly in line with the theoretical expectations
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