345 research outputs found
The relation between outburst rate and orbital period in low-mass X-ray binary transients
We have investigated the outburst properties of low-mass X-ray binary
transients (LMXBTs) based on a comprehensive study of the outbursts observed in
the past few decades. The outburst rates were estimated based on the X-ray
monitoring data from Swift/BAT, RXTE/ASM and MAXI, and previous reports in the
literature. We found that almost all LMXBTs with the orbital period below
12 hr showed only one outburst in these observations. There are
systematic difference in the outburst rate between long-period ( 12 hr) and short-period ( 12 hr) systems. We
infer that mass transfer rate is responsible for the systematic difference,
since the disk instability model (DIM) suggested that the mass transfer rate is
a key factor affecting the quiescence time. The difference in outburst rate
between long-period and short-period LMXBTs is probably due to the different
mass transfer mechanism at different evolutionary stages of the donors. Based
on the evolutionary tracks of single stars, we derived the critical orbital
period for X-ray binaries that harbor a subgiant donor in various metallicity.
The critical orbital period (12.4 hr) is consistent with the
above orbital period boundary obtained from the statistics of outburst rates.
Furthermore, we found a negative correlation between the outburst rate and the
orbital period in the samples for which the luminosity class of the donor star
is III/IV. The best-fitting power-law index for the black hole subsamples is
roughly consistent with the theoretical prediction for those systems with a
donor star evolved off the main sequence.Comment: 15 pages, 2 figures, 1 table; accepted by Ap
Mass Ratio Distribution of Hierarchical Triple Systems from the LAMOST-MRS Survey
Hierarchical triple-star systems consists of three components organised into
an inner binary (,) and a more distant outer tertiary ()
star. The LAMOST Medium-Resolution Spectroscopic Survey (LAMOST-MRS) has
offered a great sample for the study of triple system populations. We used the
Peak Amplitude Ratio (PAR) method to obtain the mass ratio (,
) of a triple system from its normalised spectrum. By
calculating Cross-Correlation Function (CCF), we determined the correlation
between the mass ratio (/(+)) and the
amplitude ratio (/(+)). We derived of
and between 0.2 and 0.8. By fitting a power-law
function of the corrected distribution, the
are estimated to be ,
and for A, F and G type stars. The derived
-values increase as the mass decrease, indicating that
less massive stars are more likely to have companion stars with similar masses.
By fitting a power-law function of the corrected
distribution, the are estimated to be
, and for G, F and A type
stars, respectively. The -values show a trend of
growth toward lower primary star masses
The environmental dependence of Spitzer dusty Supernovae
Thanks to the mid-infrared capability offered by Spitzer, systematic searches
of dust in SNe have been carried out over the past decade. Studies have
revealed the presence of a substantial amount of dust over a broad range of SN
subtypes. How normal SNe present mid-IR excess at later time and turn out to be
dusty SNe can be affected by several factors, such as mass-loss history and
envelope structure of progenitors and their explosion environment. All these
can be combined and related to their environmental properties. A systematic
analysis of SNe that exploded under a dusty environment could be of critical
importance to measure the properties of the dust-veiled exploding stars, and
whether such an intense dust production process is associated with the local
environment. In this work, we firstly use the IFS data to study the
environmental properties of dusty SNe compared to those of normal ones, and
analyze correlations between the environmental properties and their dust
parameters. We find that dusty SNe have a larger proportion located at higher
SFR regions compared to the normal types. The occurrence of dusty SNe is less
dependent on metallicity, with the oxygen abundance spanning from subsolar to
oversolar metallicity. We also find the host extinction of dusty SNe scatters a
lot, with about 40% of dusty SN located at extremely low extinction
environments, and another 30% of them with considerably high host extinction of
E(B-V)>0.6 mag.Comment: 20 pages, 15 figures, submitted to Ap
RNA-Seq Analyses of the Role of miR-21 in Acute Pancreatitis
Background/Aims: Our previous study demonstrated that a deficiency of microRNA 21 (miR-21) protects mice from acute pancreatitis, yet the underlying molecular networks associated with miR-21 in pancreatitis and pancreatitis-associated lung injury remain unexplored. Methods: We used next generation sequencing to analyze gene expression profiles of pancreatic tissues from wild-type (WT) and miR-21 knockout (KO) mice treated with caerulein by using a 1-day treatment protocol. The Database for Annotation, Visualization, and Integrated Discovery gene annotation tool and Ingenuity Pathway Analysis were used to analyze the molecular pathways, while quantitative real-time PCR, western blotting, and immunohistochemistry were used to explore the molecular mechanisms. Results: We identified 152 differentially expressed genes (DEGs) in pancreata between WT and KO mice treated with caerulein. Cellular biogenesis and metabolism were the major pathways affected between WT and KO mice, whereas cell death and inflammatory response discriminated between WT and KO mice under acute pancreatitis. We validated 16 DEGs, consisting of 6 upregulated genes and 10 downregulated genes, involved in pancreatic injury. In particular, the upregulation of Pias3 and downregulation of Hmgb1 in KO pancreata coincided with a reduced severity of pancreatitis. In addition, we found Hmgb1 stimulation resulted in the overexpression of miR-21 in peripheral blood mononuclear cells, and deletion of miR-21 led to a reduction of caerulein-induced acute pancreatitis-associated lung injury by repressing Hmgb1 expression. Conclusion: Our data support the hypothesis that miR-21 modulates the inflammatory response during acute pancreatitis through the upregulation of Pias3 and downregulation of Hmgb1. Our findings further underscore a role for miR-21 in the promotion of acute pancreatitis
Multidifferential study of identified charged hadron distributions in -tagged jets in proton-proton collisions at 13 TeV
Jet fragmentation functions are measured for the first time in proton-proton
collisions for charged pions, kaons, and protons within jets recoiling against
a boson. The charged-hadron distributions are studied longitudinally and
transversely to the jet direction for jets with transverse momentum 20 GeV and in the pseudorapidity range . The
data sample was collected with the LHCb experiment at a center-of-mass energy
of 13 TeV, corresponding to an integrated luminosity of 1.64 fb. Triple
differential distributions as a function of the hadron longitudinal momentum
fraction, hadron transverse momentum, and jet transverse momentum are also
measured for the first time. This helps constrain transverse-momentum-dependent
fragmentation functions. Differences in the shapes and magnitudes of the
measured distributions for the different hadron species provide insights into
the hadronization process for jets predominantly initiated by light quarks.Comment: All figures and tables, along with machine-readable versions and any
supplementary material and additional information, are available at
https://cern.ch/lhcbproject/Publications/p/LHCb-PAPER-2022-013.html (LHCb
public pages
Study of the decay
The decay is studied
in proton-proton collisions at a center-of-mass energy of TeV
using data corresponding to an integrated luminosity of 5
collected by the LHCb experiment. In the system, the
state observed at the BaBar and Belle experiments is
resolved into two narrower states, and ,
whose masses and widths are measured to be where the first uncertainties are statistical and the second
systematic. The results are consistent with a previous LHCb measurement using a
prompt sample. Evidence of a new
state is found with a local significance of , whose mass and width
are measured to be and , respectively. In addition, evidence of a new decay mode
is found with a significance of
. The relative branching fraction of with respect to the
decay is measured to be , where the first
uncertainty is statistical, the second systematic and the third originates from
the branching fractions of charm hadron decays.Comment: All figures and tables, along with any supplementary material and
additional information, are available at
https://cern.ch/lhcbproject/Publications/p/LHCb-PAPER-2022-028.html (LHCb
public pages
Measurement of the ratios of branching fractions and
The ratios of branching fractions
and are measured, assuming isospin symmetry, using a
sample of proton-proton collision data corresponding to 3.0 fb of
integrated luminosity recorded by the LHCb experiment during 2011 and 2012. The
tau lepton is identified in the decay mode
. The measured values are
and
, where the first uncertainty is
statistical and the second is systematic. The correlation between these
measurements is . Results are consistent with the current average
of these quantities and are at a combined 1.9 standard deviations from the
predictions based on lepton flavor universality in the Standard Model.Comment: All figures and tables, along with any supplementary material and
additional information, are available at
https://cern.ch/lhcbproject/Publications/p/LHCb-PAPER-2022-039.html (LHCb
public pages
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